Regents Physics Wells

bistredingdongMechanics

Oct 31, 2013 (3 years and 7 months ago)

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Regents Physics

Wells


Mechanics
-

HW Assignments


Kinematics


HW01
-
12

-

Speed, Velocity, Vectors, Acceleration, Free Fall, Graphing Motion, Projectiles


Dynamics
-

HW14
-

HW23

-


Newtons

laws
, Circular, Gravitation


Work/Energy
-

HW24
-
HW26

-

Work
-
Power
-
Energy

& Conservation


Impulse/
Momen
t
um

-

HW2
7
-
28

-

Impulse & Momentum


NOTE:
All HW should be
done on
loose
-
leaf

to be turned in.

It
should be stapled before you enter the classroom and is due at the
beginning of the period. No late HW accepted. It should NOT BE
SQUEEZED into the small spaces within this packet. You do not need to
rewrite questions, but your work should be on lo
ose
-
leaf. Graphs and
diagrams done in this packet can be attached to your loose
-
leaf.

Your
work should be neat
,

organized and clear as done in class and should
have formulas with substituted values and
units on all numbers
. You
will lose points for wo
rk that does not meet these criteria.



Quiz:
as indicated in class, you will be quizzed often on these HW
problems.



Physics HW #1










PAGE 1 of 1


Homework assignments can be downloaded from the website if needed
http://wells.xroad.com



A.

Express the following in standard Scientific Notation form and E notation
-



1.

-
32.74 million dollars


2.

1744000000000 tacos


3.

0.000026006 nm


B. Convert the following scientific notation numbers
into common form


1. 5.6 x 10
5

ft


2. 3.574 x 10
-
5

in


3.
-
2.154e9 lbs


4. 3.05404e
-
3 kg


C. Solve the equations shown below by plugging in the assigned values. Write out the operation you will perform in
E notion form. Then complete the opera
tions using a calculator, and state answers in scientific notation form.
Put a
‘distance’ type unit of your choice on each answer


1.

X =
-
3.6 x 10
-
24



Y =
-
3.6 x 10
-
26


X + Y




2.

X =
-
7.612 x 10
19


Y = 3 x 10
7


X
2

* Y




3.

X =
-
5.09 x 10
-
13



Y = 6

x 10
16


X / Y
2






D. Solve the following equations for the unknown variable; put a ‘time’ type unit of your choice on each answer
(show work)


1.

-

t
2

+ 81 = 0



2.

6t+ 16 = 20




3.


a = 49



ANSWERS

A1)
-
3.274x10
7

or
-
3.274e7 dollars, A2) 1.744x10
12

or 1.744e12 tacos, A3) 2.6006x10
-
5

or 2.6006e
-
5 nm

B1) 560000 ft, B2) 0.00003574 in, B3)
-
2154000000 lbs, B4) 0.00305404 kg

C1)
-
3.64x10
-
24

m, C2) 1.74x10
47

in, C3)
-
1.4x10
-
46

ft

D1) t = 9 sec, D2) t = 0.667 min, D3) a = 2401 hr



Physics HW #2










PAGE 1 of 2


A.) Conversions


on a separate piece of paper, perform the following conversions
using the factor label method
.



1)

0.0000001326 m

to

a)

m


b) nm


c) mm



2)

50 nm to mm

3)

200

s to s

4)

2x10
-
8

mm to nm

5)

1.53 kg
to g

6)

3x10
6

Ms to sec

7)

5x10
-
8

nm to pm

8)

.000015

Tg to kg





B.) Solve the following triangle problems for the
unknown sides. The angle that appears to be a right
angle actually is.



1.



22 in







x










17 in


2.




x


29 mm






= 14.3




y



3.











50.4 in



78.4 cm




y





























C.) Find
all unknown angles

in the triangles below.
The angle that appears to be a right angle actually is.


1.)



1



22.9 m

















2





53.4 m










2.)





1 = 67.42



8.75 m











3.3
6 m


2







3.)

2




13.2 ft





1



10.8 ft





Answers


A:

1a) 0.1326

m
, 1b) 132.6 nm 1c) 0.0001326 mm, 2) 5x10
-
5
mm, 3) 2x10
-
4
sec, 4) 2x10
-
2

nm, 5) 1530 g, 6) 3x10
12

sec, 7)
5x10
-
5

pm, 8) 1.5x10
4

kg



B:

1) 27.8

in, 2) x=117.4 mm, y =113.8 mm,

3) y=101.2 cm or 39.84 in


C
: 1) 66.8°, 23.2°, 2) 22.6° 3) 35.1°, 54.9°

D) Graphing











PAGE 2 of 2


1) Using the information in the table, construct a graph of Force vs Elongation on the grid. A) Label each axis with the
appropriate physical quantity and unit B) Plot
the data points for period versus pendulum
length. C) Draw the best
-
fit line or curve fo
r the
data graphed



D) Find the slope of the line






2) Using the information in the table, construct a graph on the grid. A) Label each axis with the appropriate physical
quantity and unit. B) Mark an appropriate scale on each axis. C) Plot the data p
oints for period versus pendulum
length. D) Draw the best
-
fit line or curve for the data graphed. E) Using your graph, determine the period of a
pendulum whose length is 0.25 meter.





























ANSWERS

1)

Best fit line is linear, Plot point 0,0 and make sure its ‘best fit’ not connect the dots, d) = 4 N/m


2)

Best fit line is a
curve, do NOT connect 0,0 e) 1 sec



Physics HW #3












PAGE 1 of 1



HW3

1.) A human hair is approximately
45

μ
m

in diameter. Express this diameter in m.


2.)The distance between the sun and the earth is about 1.5 x 10
11

m. Express this distance in km and in Gm.


3.) Heather and Matthew walk eastward with a speed of
0.58

m/s. If it takes them 34 min to walk to th
e store, how far
have they walked in meters.


4.) What is the shortest possible time that a bug could drift across a bowl of water with a diameter of
6.3

cm if the bug
was moving at a constant speed of 3.5 mm/sec.


5.) An athlete swims from the north end to the south end of a
40

m pool in
16

s and makes the return trip to the
starting position in
22

s. (a) What is the average velocity for the first half of the swim (b) what is the average velocity
for the second half

of the swim (c) What is the average velocity for the roundtrip (d) What is the average speed for the
roundtrip


6.) A runner travels 10 m east, the travels 4 m west. a) What is his total distance travelled b) What is his
displacement for the trip.


7.) T
wo cars are traveling east on a desert road separated as shown in the diagram below. After 5 seconds they are
side by side at the next telephone pole. The distance between each pole is
35

m. Find (a) the displacement of car A
after 5 sec, (b) the displa
cement of car B after 5 sec, (c) the average velocity of car A during 5 sec, (d) the average
velocity of car B during 5 sec.


Initially


BEFORE




5 sec later

AFTER




pole1


pole2


pole3



pole1


pole2


pole3










8.) An object moves halfway around the spherical earth (earth has a known radius that is given on the reference table,

assume it is circular allowing you to use circle formulas). It takes this object 1 day to cover the distance travelled
halfway around the earth. (a) What is the average speed of this object (in m/s) (b) What is the average velocity of this
object. (Be
sure to make a sketch and label the displacement as well as distance)


9) A high
-
speed train in Japan travels a distance of 300 kilometers in 3.60 x 10
3

seconds. What is the average speed
of this train in m/s?







HW3 Answers




1) 0.000045 m, 2a) 1.5x1
0
8

km b) 150 Gm, 3) 1183.2 m, 4) 18 s,

5a) 2.5 m/s south b) 1.82 m/s north c) 0 d) 2.105 m/s, 6a) 14m, 6 m east,

7a) 35 m east, 70 m east, 7 m/s east, 14 m/s east,

8a) 231.62 m/s, b) 147.45 m/s across the earth, 9) 83.3 m/s



Car A

Car
B

Car A

Car
B


6690


km

Physics HW #4












PAGE 1 of 1


1.) Sally travels by car from one city to another. She drives for 30 min at
65

km/h, 12 min at
80

km/h, spends 10 min
eating lunch and then travels 45 min at
25

km/h. Determine the average speed for the entire trip (in km/hr).





2.) The average speed of an orbiting space shuttle is
25800

km/h,


The shuttle is orbiting at a radial distance of 6690 km measured from the earth center.

a) Determine the time required for it to
circle

earth in hrs.

b) What was the average velocity of the shuttle over one full orbit.





3.) A bacteria moves 30
mm

across a Petri dish at a speed of
1.25

nm/sec
. How long, in hrs does it take the bacteria
to move across the dish


4.) Two students walk in the same direct
ion along a straight path, at a constant speed


one at
0.7

m/s and the other
at
1.72

m/s. Assuming that they start at the same point and the same time, how much sooner does the faster student
arrive at a destination 780 m away?


5) A car travels 90 meter
s due north in 15 seconds. Then the car turns around and travels 40 meters due south in 5.0
seconds. a) What is the magnitude of the average velocity of the car during this 20 second interval?, b) What was the
average speed over the 20 seconds?



6) For th
e following data, make a graph of distance vs. time

Time (s)

Distance (m)

5

1.5

10

4.8

15

5.5

20

7.6

25

11



a)

Label your axis


b)

Draw a best fit line


c)

Calculate the slope


d)

What does the slope

represent, and why?







HW4 Answers



1) 41.6 km/hr, 2a) 1.63 hrs, b) zero, 3) 6666.67 hrs, 4) 660.8 sec, 5a) 2.5 m/s north, b) 6.5 m/s

6) Best fit

is linear, do NOT connect 0,0 c) 0.44 m/s, d) it’s the velocity since its distance over time.





















































































































































Physics HW #05













PAGE 1 of 1


HW5 Questions

1.) For the quantities below, define each as a vector or scalor


(a) the acceleration of a plane


(b
) the number of passengers on a plane


(c) the time required to complete the flight


(d) the displacement of the flight


(e) the fuel needed for the flight


2.) Can two vectors with unequal magnitudes have a resultant of zero? Explain


3.) How is the equil
ibrant found?


4.) What is another way of saying 30 km/hr @ 30° north of east

(give the alternate direction). Sketch the vector and
label the angle on your sketch.


5.) Three vectors are shown,

sketch the resultant of these three vectors if they were

added




6.) In the diagram below, vector
R
represents the resultant of vectors
x

and
y
. Draw vector
y

(In other words,
determine the vector that you would need to add to vector
x

in order to make vector
R
)








x






R


7.) The vector
below is drawn using a scale 1 cm = 3 m/s. Use a ruler and a protractor to measure and state the
magnitude and direction of the vector. (extend the length of the vector so you can accurately read it














N










8.) Vectors
n
=
5

m/s east,

m

=
12

m/s south.

(a) Determine
n + m

mathematically (b) find the equilibrant for the answer to (a)


9.) A fox runs
8

m heading 25° north of west and then turns and heads west
4

m. Determine

the fox’s displacement
graphically (note that displacement is a vector quantity).


10.) A taxicab heads north
4

km on 1
st

st. and turns west onto 51
st

st. He heads west
1.5

km on 51
st

st and turns
south on lex. The cab finished his fare by traveling
2

km south on lex. Mathematically determine the displacement of
the cab
(note: a right triangle is formed as a result of the 4 movements)




HW5


Answers

1) vector, scalar, scalar, vector, scalar, 2) No, cant cancel if unequal, 3) it’s the opposite of t
he resultant,

4) 30 km/hr @ 60
°

E of N, 5) redraw each and link head to tail, gives arrow pointing up
-
right for resultant, 6) y points
up and right, 7) measured (2.5cm) = 7.5 m/s @ 22
° N of E, 8a) 13 m/s @ 67.4° S of E, b) 13 m/s @ 67.4° N of W,

9) 11.8

m @ 17° N of W, 10) 2.5 km @ 53
.13° N of W


Intentional Blank Page










































Intentional Blank Page



Physic
s HW 6












PAGE 1 of 2



Beginning with this HW assignment, HW’s will be given in 2 parts. This handout is part A of the HW. Part B
of the HW will

be multiple choice problems assigned from the castle learning website. These multiple choice
problems are due the same day this HW is due and will count as part of the grade and will also be potential
HW quiz questions.


HW6A Questions


1. Three student
combine two vectors with magnitudes of 55 and 25 units each and each get different answers of 85,
20 and 55 units. Explain which answer is correct and why.


2. Can a vector have a component equal to zero without being zero itself? Explain with an examp
le.


3. What are the x and y components of a vector
V
a

=
50

mph 10


east of north


4. The x component of a vector is
5

m West. The y component of this vector is
25

m North. What is the vector that
has these components.


5. What are the x and y components of a vector
K

=
400

km/hr @ 75


west of south.


6. Vectors are defined as:


A

= 3 m east


B

= 7 m north

Determine

(a)
A

-

B



(b) 2*
B

-

A


7. A boat in still water travelling at
40

m/s east enters a stream with a current

of 15 m/s north.

A) What is the resultant velocity of the boat in the water (Solve both graphically and mathematically and show each).
B) If the stream is 100 m wide, how long does it take the boat to cross?


8. Birds fly to their destination using the f
ollowing paths: 300 km N, 100 km E, 500 km @ 65


W of N. Sketch the
vector picture and solve for the resultant displacement graphically.


9. Two vectors
G
=
10

ft @ unknown angle and
H
=
14

ft @ unknown angle are to be added to each other to get a
resultant v
ector. What is the maximum and minimum possible value of this addition? Be sure to show sketches of
the two situations where you get the maximum and minimum.


10. A storm travels to a destination in two parts. In part I the storm travels south at 25 km/
hr for
0.75

hrs and then
turns and travels in section II at 41 km/hr @ 30° east of south for
1.2

hrs. (a) Determine the displacement of each
separate section of the trip, (b) Graphically, determine the total resultant displacement of the storm.


11. A pl
ane travelling at 250 m/s north in still air enters a crosswind of 75 m/s west. a) What is the resultant
velocity of the plane. b) If the 75 m/s was a tailwind directed north, what would the resultant velocity of the plane
be?


12. Graphing question on
next page


HW6B


Castle Learning





HW6 Answers



1) based on max and min values, only 55 is possible, 2) yes, a vector in the y direction has zero x
component, 3) Vx=8.68 mi/hr E, Vy=49.24 mi/hr N, 4) 25.5m @ 11.31° W of N (or 78.69° N of W),

5) Kx
=386.4 km/h W, Ky=103.5 km/h S, 6a) 7.62 m @ 66.8° S of E, b) 14.32m @ 12.09° W of N,

7a) 42.72 m/s @ 20.56° N of E, b) 2.5 sec, 8) 621.4 km @ 34.36° W of N (or 55.61° N or W)

9) max=24 ft, min=4 ft, 10a) 18.75 km, 49.2 km, b) 66.11 km/hr @ 21.85° E o
f S. 11a) 261 m/s @ 73.3° N of W,
b) 325 m/s north

PAGE 1 of 2





12) A drag racer test drives a 100 m race strip with a variety of average velocities over the 100m distance. The time
and velocity data is shown below.


velocity
(m/s)

time (s)

10

10.00

20

5.00

30

3.33

40

2.50

50

2.00

60

1.67


a)

Make a graph of velocity vs time and draw a best fit line or curve to fit the data. Label the axis

b)

What specific type of relationship between velocity and time does this graph show.









Answer

12)
graph is a half parabola, it is an inverse relationship


Physics HW #7












PAGE 1 of 2


HW7A Questions


Problems 1
-
5 (Put your answers on the answer sheet and use extra paper if needed)


1.) A bowling ball with a negative initial velocity slows
down as it rolls down the lane toward the pins. Is the bowling
ball’s acceleration positive or negative as it rolls toward the pins? Explain your answer using the equation a =
Δ
v / t


2.) Two cars are moving in the same direction in parallel lanes along
a highway. At some instant, the instantaneous
velocity of car A exceeds the instantaneous velocity of car B. Does this mean that car A’s acceleration is
DEFINITELY greater than car B’s? Explain, and specifically give an example of how it does or does no
t show this.


3.) What would be the acceleration of a turtle that is moving with a constant velocity of 0.25 m/s to the right?, explain.


4.) A car is moving along the roadway with oil dripping from the bottom. For each oil drip pattern shown below,
expla
in specifically how the car would be moving to produce the pattern shown.




a)























b)






















c)










● ● ● ● ● ● ● ● ● ● ●





5.) If a car is traveling eastward, can its acceleration be westward?

Explain and use an example.


6.) Nathan accelerates his skateboard uniformly along a straight path directed east from rest to
7.5

m/s in 2.5 sec. (a)
what

is Nathan’s acceleration, (b) what is Nathan’s displacement during this time interval, (c) what is Nathan’s
average velocity during this time interval


7.) A ball initially at rest rolls down a hill with an acceleration of 3.3 m/s
2
. If it accelerates for

5.5

sec, how far will it
move?


8.) A plane lands with a velocity of
120

m/s and accelerates at a maximum rate of


6 m/s
2

(a) from the instant the
plane touches the runway, what is the minimum time needed before it can come to rest. (b) Can this plane

land on
an aircraft carrier with a runway that is 0.80 km long, justify your answer.


9.) A sailboat starts from rest and accelerates at a rate of 0.21 m/s
2

over a distance of
245

m. (a) find the magnitude
of the boats final velocity (b) find the time it

takes the boat to travel this distance.


10.) A car starting at an unknown initial speed accelerates uniformly over
12

m in
5

seconds at which time it has
stopped. What is the initial speed of the car? (need multiple steps).


11.) Graphing question on ne
xt page








HW7B


Castle Learning


HW7A Answers

-

1)

v needs +a to slow, 2) no, accel is changing velocity and not related to inst. velocity. 3) zero,

4a) speed up, b)constant, c) slowing then constant, 5) yes, move east and slow down, 6a) 3 m/s
2
east, b) 9.38 m east,
c) 3.75 m/s east, 7) 49.91 m, 8a) 20 sec, b) 1200 m needed so NO, 9a) 10.14 m/s, b) 48.29 sec, 10) 4.8 m/s




PAGE 2 of 2


11) Using the information in the data table, construct a graph on the grid

a) Plot the data points.


b
) Draw the line of best
-
fit.


c) On the same grid, sketch a line representing an object decelerating uniformly in a straight line.


d) find the slope of the best fit line


e) the slope of this line, ∆y / ∆x, represents what physical quantity.













Answer

11) linear best fit line, connect 0,0. Using only pts ON the line, find slope ~ 1.2 m/s/s, slope ∆y/x is ∆v/t so is accel.



Physics HW #8











PAGE 1 of 1



HW8A Questions


1. A car starts from rest and travels for 5 sec with a unifor
m acceleration of +
1.1

m/s
2
. The driver then applies the
brakes causing a uniform acceleration of
-
0.5

m/s
2
. If the brakes are applied for 3 sec (a) how fast is the car going
at the end of the braking period, and (b) how far has it gone from its start.


2. A ball is rolling forward with an unknown initial velocity and rolls for
4

seconds over
12

m. The ball accelerates at
a rate of 0.6 m/s
2
. Find (a) the average velocity of the ball, (b) the initial velocity of the ball and (c) the final velocity
of t
he ball.


3. A car travels east at an average speed of 10 m/s for 200 m and then continues east for 350 m at an average speed
of 4 m/s. Determine the average velocity of the car over the whole trip.


4. Force A with a magnitude of 5.6 newtons and force B

with a magnitude of 9.4 newtons act concurrently on point P.







a) Determine the scale used in the diagram.

b) On the diagram, use a ruler and protractor to construct a vector representing the resultant of forces A and B.


c) Determine the magnitude

of the resultant force.





HW8B


Castle Learning




















HW8A Answers



1a) 4 m/s, b) 28m, 2a) 3 m/s forward, b) 1.8 m/s forward, c) 4.2 m/s forward, 3) 5.12 m/s east,
4a) 1cm = 2N, b) redraw head to tail to get a resultant pointing up and le
ft, c) 7.4 N

Physics HW #9

& 10










PAGE 1 of
2


Questions 1
-
2


1) During which interval is the cart moving forward at constant speed?


2) During which interval is the cart increasing speed





Questions 3
-
6




3) What is the carts velocity at 6 seconds


4) When is the cart stopped


5) What is the displacement of the vehicle at 5 seconds


6) How far did the cart travel over the entire trip





Questions 9
-
11










PAGE 2

of
2



7)
At what
times is the car stopped?




8)
Deter
mine the carts acceleration at 7

seconds.




9)
How far did the car travel from 0
-
3 seconds?




10)
At what times was the speed constant?




11)
How far did the car travel from 5
-
6 seconds?




HW9B
-
10B


Castle Learning

for both


Answers
-

HW9A
-
10A

1) BC, 2) AB, 3)


2 m/s, 4) 2
-
4 sec, 5) +6m, 6) 16 m, 7) 0 sec, 10 sec, 8)


7.5 m/s
2
, 9) 25 m, 10) 1
-
3, 5
-
6 sec,
11) 25 m



Intentional Blank Page



Physics HW #11












PAGE 1 of 2


HW11A Questions



Unless otherwise indicated, assume no air resistance in all problems


1.) A coin is tossed vertically upward (no air resistance). (a) Describe what happens to the velocity over the entire
course of its path in the air (b) does the acceleration increase,

decrease or remain constant while in the air?


2.) A pebble is dropped down a well and hits the water
1.25

sec later. Determine the distance from the top of the
well to the water below.


3.) A ball is thrown vertically upward, what are the velocity and a
cceleration at the peak where it reaches its
maximum altitude.


4.) A ball is thrown down with an initial speed of 10 m/s. A second ball is dropped from rest at the same height as
the first ball. (a) compare the acceleration of each ball while they are i
n motion. (b) compare the velocity of each
ball as they strike the ground.


5.) A flowerpot falls from a windowsill
17.5

m above the ground. (a) How long does it take and (b) with what
velocity does it hit the ground.


6.) A cannon ball is launched direc
tly upwards at an initial speed of
17.5

m/s. (a) What maximum height does it reach
and (b) how long is it in the air for over its whole up and down trip.


7
.) removed


no question


8.) What does it mean when an object reaches terminal velocity? What is t
he acceleration of an object that reaches
terminal velocity, explain.


9.) A ball is thrown upwards and returns to the thrower 3.5 seconds after it was thrown, determine (a) the maximum
height of the ball and, (b) the initial throwing speed, (c) the veloci
ty when it returns to the thrower.


10) A student throws a baseball vertically upward and then catches it. If vertically upward is considered to be the
positive direction, which graph best represents the relationship between velocity and time for the baseb
all? [Neglect
friction.]






11) Graph, next page.



HW11B


Castle Learning



HW11A


Answers

1a) dec, 0, then inc., b) a is const at
-
9.81, 2) 7.66 m, 3) v=0, a=


9.81m/s
2
, 4) same, thrown one hits faster (duh)
5a) 1.89 sec, b)

18.54 m/s,
6a) 15.63 m, b) 3.57 sec,

8) doesn’t get any faster, reaches final falling speed and has
accel=0, 9a) 15.02 m, b) 17.17 m/s, c)

17.17 m/s, 10) choice 4



PAGE 2 of 2


11) A 1.00
-
kilogram mass was dropped from rest from a height of 25.0 meters above E
arth’s surface. The speed of
the mass was determined at 5.0
-
meter intervals and recorded in the data table below.


Using the information in the data table, construct a graph on the grid, following the directions below.

-

Mark an appropriate scale on the a
xis labeled “Height Above Earth’s Surface (m).”




-

Plot the data points for speed versus height above Earth’s surface.

-

Draw the line or curve of best fit.

-

Using your graph, determine the speed of the mass after it has fallen a vertical distance o
f 12.5 meters.



ANSWER

best fit is a
curve , speed is read from the graph ~ 16 m/s



Physics HW #12

-

ignore air resistance unless otherwise indicated.



PAGE 1 of 2



HW12A Questions


1. A bullet is fired horizontally and another bullet is dro
pped simultaneously from the same height. If air resistance
is neglected, which bullet hits first, explain your answer.


2. Does a ball dropped out of a window of a moving car take longer to reach the ground than one dropped at the
same height from a car
at rest, explain.


3. A man is holding two rocks at equal heights. One is dropped and the other is thrown horizontally. (a) which rock
hits first (b) which rock will have a greater velocity when it hits


4. A certain gun type fires bullets at 60 m/s regardless of its orientation. One Bullet is fired with the gun aimed at
10° above the horizontal, a second bullet is fired simultaneously at 45° above the horizontal and a third bullet is fired
simultaneousl
y at an angle of 60°. Ignoring air resistance, answer the questions that follow and explain your choice
for each one. (a) which hits the ground first, (b) which goes the highest, (c) which has the greatest range, (d) which
has the largest x component (e)
which has the greatest acceleration


5. (A) On the diagram; construct the x and y components of the

velocity at point A. Draw them to scale in relation to the given







vector already at point A









B














A


(B)
Given that the scale used in the drawing is 1 cm = 2 m/s, use a ruler and the given scale to determine values for
the initial velocity as well as initial x and y components. Label them on the diagram.

(C) Use a ruler and the rules of projectiles to sketch

the velocity vector, as well as the x and y components of the
velocity at position B shown in the diagram. Draw it to scale and label the value of each quantity on the diagram.


6. A plane traveling at and altitude of
45

m is moving with a speed of
95

m/
s. A package is dropped out of the plane
traveling with the same horizontal velocity as the plane. What horizontal distance does the package travel before
hitting the ground?


7. A car drives horizontally off a 10 m high bridge and lands in the water be
low 20 m away horizontally from the
base of the bridge. How fast was the car traveling when it left the bridge?


8. A ball is thrown at an angle of
20
° above the horizontal relative to the ground at a speed of
23

m/s. If the ball
was caught
34.58

m away
from the thrower,(a) how long was it in the air for and (b) how high did it go.


9. A soccer ball on the ground is kicked at 8 m/s @ 40 degrees above horizontal and hits the ground at some time
later on (a) how long is the ball in the air for, (b) what is
the range of the balls motion, (c) what is the max height


10)
removed


no question



11,12,13)


continued on next page




HW12B


Castle Learning





PAGE 2 of 2


11) A machine fired several projectiles at the same angle, θ, above the horizontal. Each projectile was fired with a
different initial velocity, vi. The graph below represents the relationship between the magnitude of the initial vertical
velocity, viy, an
d the magnitude of the corresponding initial velocity, vi, of these projectiles.




a) Determine the magnitude of the initial vertical velocity of the projectile, viy, when the magnitude of its


initial velocity, vi, was 40 meters per second.


b) De
termine the angle,
θ
, above the horizontal at which the projectiles were fired.


c) Calculate the magnitude of the initial horizontal velocity of the projectile, vix, when the magnitude of its initial
velocity, vi, was 40. meters per second.


12) A
projectile is fired from the ground with an initial velocity of 250 meters per second at an angle of 60.° above


the horizontal

a) Use a protractor and ruler to draw a vector to represent the initial velocity of the projectile.


Use a scal
e of 1.0 centimeter = 50. meters per second.

b) Determine the horizontal component of the initial velocity.

c) Explain why the projectile has no acceleration in the horizontal direction.


13) A kicked soccer ball has an initial velocity of 25 meters p
er second at an angle of 40° above the horizontal, level
ground. Sketch the path of the ball’s flight from its initial position at point P until it returns to level ground.







HW12A Answers

-

1,2


same question, both hit at same time (independenc
e of motion), 3a) same time b) since
velocity is a combination of x
-
y the thrown one will hit with an larger velocity due to both x&y components together,
4a) lowest angle hits first, least time, b) big angle most time / most height, c) 45° gives max range
, d) lowest angle
most x comp, e) all same accel (
-
9.81),

5) drawing components and measuring each gives V
a
= 4.4 m/s, V
ax
= 2.4 m/s ,V
ay
= 3.4 m/s ,


V
b
= 2.6 m/s, V
bx
= 2.4 m/s

, V
by
= 0.8 m/s,

6) 287.85 m, 7) 14 m/s, 8a) 1.6 sec, 3.16 m,

9a) 1.05 sec,

b) 6.42 m , c) 1.35 m,


11a) 25 m/s, b) 39°, c) 31 m/s, 12a) draw to scale, b) 125 m/s, c) no gravity or other forces in x direction,

13) parabolic curve



Physics HW #14












PAGE 1 of

2




1


How does the i nerti a of a 2 ki l ogram rock compare to

the i nerti a of a 1 ki l ogram rock? (expl ai n)




2


If you were i n a spaceshi p and fi red a cannonbal l i nto fri cti onless space, how much force woul d have to be exerted on the
bal l to keep i t goi ng, expl ai n.





3


Whi ch has more i nerti a, a bul l et travel i ng

at 100 m/s or a bowl i ng bal l sl owly rol ling across the fl oor, expl ai n.




4


If an el ephant were chasi ng you, i ts enormous mass woul d be very threateni ng. But i f you zi gzagged, the el ephant’s mass
woul d be to your advantage. Why?





5


What i s the net

force or, equi val entl y, the resul tant force acti ng on an object i n equi l i bri um?




6


Forces of 10 N and 15 N i n the same di recti on act on an object. What i s the net force on the object?




7


Suppose a cart i s bei ng moved by a certai n net force. If t
he net force i s doubl ed, by how much does the cart’s accel erati on
change? (expl ai n or show exampl e)




8


Suppose a cart i s bei ng moved by a certai n net force. If a l oad i s dumped i nto the cart so i ts mass i s doubl ed, by how much
does the accel erati on
change? (expl ai n or show exampl e)




9


How much net force acts on a 20,000 kg rocket that accel erates at 1 m/s
2





10


If an object has no accel erati on, can you concl ude that no forces are exerted on i t? Expl ai n.





11


A rocket fi red from i ts l aunc
hi ng pad not onl y pi cks up speed, but i ts accel erati on al so i ncreases significantl y as fi ri ng
conti nues, why i s thi s so? (Hi nt: about 90% of the mass of a newl y l aunched rocket i s fuel.)






PAGE 2 of 2


12


A hori zontal force of 100 N i s requi red to pus
h a crate across a factory fl oor at a constant speed. What i s the net force
acti ng on the crate? What i s the force of fri cti on acti ng on the crate, justi fy your answers.




13


The force of gravi ty i s twi ce as great on a 2kg rock as on a 1 kg rock. Why

does the 2 kg rock not fal l wi th twi ce the
accel erati on?





14


Why do a coi n and a feather i n a vacuum tube fal l wi th the same accel erati on?





15


When a hammer exerts a force on a nai l, how does the amount of force compare wi th that of the nai l on
the hammer?





16


When swi mmi ng, you push the water backward


cal l thi s acti on. What i s the reacti on force?




17


When a ri fl e i s fi red, how does the si ze of the force of the ri fl e on the bul l et compare wi th the force of the bul l et on the
ri fl e? Ho
w does the accel erati on of the ri fl e compare wi th that of the bul l et? Defend your answer.




18


How can a rocket travel i n space where there i s no ai r to “push agai nst”?





19


If you hi t a wal l wi th a force of 200 N, how much force i s exerted on you?





20


A speedi ng bus makes contact wi th a bug that spl atters onto the wi ndshi el d. Because of the sudden force, the unfortunate
bug undergoes a sudden decel erati on. Is the correspondi ng force that the bug exerts agai nst the wi ndshi el d greater, l ess, or

the

same? Is the resul ti ng decel erati on of the bus greater than, l ess than, or the same as that of the bug? Expl ai n.







Physics HW #15












PAGE 1 of 1


1


What i s the effect of fri cti on on a movi ng object?




2


What i s the cause of fri cti on, an
d i n what di recti on does i t act wi th respect to the moti on of a sl i di ng object?





3


If the force of fri cti on acti ng on a sl i ding crate i s 100 N, how much force must be appl i ed to mai ntai n a constant vel oci ty?

What wi l l be the net force acti ng on the c
rate? What wi l l be the accel erati on?







4


Stati c fri cti on said to be a vari able force whi l e ki neti c fri cti on i s not. Gi ve an exampl e of thi s and expl ai n ful l y.







5


A man pushes hori zontal l y on a box that rests on a hori zontal rough surface.
Why i s i t harder to start movi ng the box then i t
i s to keep i t movi ng?






6


What i s the wei ght of 2 ki l ograms of yogurt?




7


Susi e fi nds she wei ghs 300 N. Cal cul ate her mass.





8


When a junked car i s crushed i nto a compact cube, does i ts mass c
hange? Its vol ume? Its wei ght?






9


A moon rock has a mass of 10 kg on the moon. What i s i ts mass on the earth?





10


An object wei ghs 500 N on the moon. What i s i ts mass?






Intentional Blank Page



Physics HW #16












PAGE 1 of 2


1.) (a
) Draw a free body di agram of a footbal l whi l e i t i s bei ng drop ki cked and the foot i s i n contact wi th the bal l. Si nce i t i s

drop
ki cked, the bal l i s not i n contact wi th the ground. (b) Draw the free body di agram of the bal l whi l e i t i s movi ng i n the fri
cti on
free ai r after i t has l eft the pl ayers foot.









2).. removed

3
.) Identi fy the acti on
-
reacti on pai rs i n the fol l owi ng si tuati ons:









ACTION FORCE



REACTION FORCE


(a) a person takes a step


(b) a snowbal l hi ts someone i n the back


(c) a

basebal l pl ayer catches a bal l i n a gl ove


(d) a gust a wi nd (ai r) stri kes a wi ndow



4.) Draw a free body di agram for each of the fol l owi ng si tuati ons


(a) a projecti l e at the top of i ts trajectory i n moti on i n the presence of ai r resi stance


(b) a rocke
t l eavi ng the l aunch pad wi th i ts engi nes operati ng


(c) a heavy crate bei ng pushed up a rough i ncl i ne.













5.) A bag of sugar has a mass of 2.26 kg.


(a) What i s i ts wei ght on the moon


(b) The accel erati on of gravi ty on Jupi ter i s 2.64 ti mes that

on earth. How much woul d the bag wei gh there.






PAGE 2 of 2


6.) Is i t possi bl e for an object to be movi ng i f no net force i s acti ng on i t? Expl ai n.






7.) If an object i s at rest can we concl ude that no external forces are acti ng on i t, expl ai n.







8.) An object thrown i nto the ai r momentari l y stops at the hi ghest poi nt i n i ts path. Is i t i n equi l i brium at thi s poi nt, ex
pl ai n.








9.) What physi cal quanti ty i s a measure of the amount of i nerti a an object has?








10
-
11
.)



removed

















Physics HW #18













PAGE 1 of 2







RETURN OF CASTLE LEARNING


Castle Learning assignments will return and they will begin to have review
problems on them as well from prior topics



HW 18A


Problems Below

These are not the easiest problems in the world. Be careful about how you draw the FBD diagrams, read the details
carefully. Give them a shot and see if you can do them, struggle with them a little, that’s how you learn. Hints are
posted on the website w
ith diagrams to make sure your FBDs are correct. If you have tried to figure these out and are
stuck, just go and look at the hints … they are infinitely helpful.


http:/wells.xroad.com


1) A 3.2 kg bucket of water is raised from a well by a rope.
If the upward acceleration of the bucket is 1.75 m/s
2
, find
the force exerted by the rope on the bucket


2) A woman pushes on a 20 kg lawnmower with a force of 23.5 N directed at 30
°

below the horizontal and towards the
right. The mower moves to the right

and a 4.2 N friction force opposes the motion of the mower.


(a) Determine the acceleration of the mower


(b) Determine the normal force acting on the mower


3) You, with your infinite power can exert a maximum force of 100 N on any object. You use yo
ur maximum force on
an object and push it horizontally on a surface that will exert 25 N of friction force and cause the block to accelerate at
2 m/s
2
. Are you a wimp?, justify your answer


(You will be considered a wimp if you can push less than 50 kg o
f
mass around, so you therefore need to find the mass of the object you push and compare it.)


4) A 100 N box is pulled with 2 forces. A 23 N force directed to the right and a 9 N force directed at 60
°
up from the
horizontal and towards the left. The box

moves to the right at a constant speed and a friction force acts to retard
(slow) the motion.


a.) Determine the friction force acts on the box.


b.) Determine the normal force acts on the box.


5)

In the scal ed di agram, two forces,
F
1 and
F
2, act

on a 4.0
-
ki l ogram bl ock at poi nt
P
. Force
F
1 has a magni tude of 12.0
newtons, and i s di rected toward the ri ght.

a) Usi ng a rul er and the scal ed di agram, determi ne the magni tude of
F
2 i n newtons



b) Determi ne the magni tude of the net force
acti ng on the bl ock.


c) Cal cul ate the magni tude of the accel erati on of
the bl ock.









6) Graph question on next page


Answers: 1) 37 N, 2a) 0.81 m/s
2
, b) 208 N, 3) Since you can only push 37.5 kg, you are a wimp,

4a) 18.5 N, b) 92.2 N, 5a) measuring F1 we find scale


1cm = 2.31 N, then measuring F2 we get 9 N

5b) 3N, c) 0.75 m/s
2



HW18B


Castle Learning, login and complete assignment


PAGE

2 of 2


6) A constant force is applied to a variety of masses and the acceleration of each mass is measured as shown in the
table below.


Mass (kg)

Accel erati on (m/s
2
)

10

5.00

15

3.33

20

2.50

25

2.00

30

1.67

35

1.43

40

1.25


Create a graph of acceleration vs mass for the provided data, properly labeling the graph and axis.













































































































































































































































































































What specific type of mathematical relationship does this graph indicate? Does this
relationship make sense in
relation to Newton second law?



Physics HW #19













PAGE 1 of 1


HW19 A
-

Problems




1) A 10 ki l ogram rubber bl ock i s pul l ed hori zontal ly wi th a hori zontal l y applied force and i t moves at a constant vel oci ty of

2 m/s
acr
oss a sheet of i ce. a) Cal cul ate the magni tude of the force of fri cti on acti ng on the bl ock. b) Cal cul ate the pushi ng force


2) A 25 kg chai r i ni ti ally at rest on a hori zontal fl oor requi res a 380 N hori zontal force to set i t i n moti on. Once the cha
i r i s
i n
moti on, a 340 N hori zontal force keeps i t movi ng at a constant vel oci ty. (a) fi nd the coeffi ci ent of stati c fri cti on between

the
chai r and the fl oor (b) fi nd the coeffi ci ent of ki neti c fri cti on between the chai r and the fl oor.


3) A student moves a box

of books down the hal l by pul l i ng on a rope attached to a wood box. The student pul l s wi th a force of
170 N at an angl e of 20° above the hori zontal. The WOOD box has a mass of 28 kg and i t i s pul l ed across a WOOD fl oor. Fi nd
the accel erati on of the box
.


4) A 2.75 kg bl ock i s pushed al ong the cei l i ng wi th a constant appl i ed force of 85
N that acts at and angl e of 55° wi th the hori zontal as shown i n the fi gure. The
bl ock accel erates to the ri ght at 6 m/s2. Determi ne the coeffi ci ent of ki neti c
fri
cti on between the bl ock and the cei l i ng.

The FBD i s tri cky for thi s probl em, remember that the normal force al ways
comes outward from the surface. Refer to websi te for further hel p.


5) A box of books wei ghi ng 319 N i s on a surface wi th a coeffi ci ent of

ki neti c fri cti on between the box and the fl oor of 0.57 and a
coeffi ci ent of stati c fri cti on of 0.62

(a) A hori zontal force i s appl i ed to the box. What i s the mi ni mum amount of force needed to set the box i nto moti on.


6) … removed


7) A 10 kg box i s
pushed across a surface at a constant speed ori ented as shown, and 49 N of pushi ng force i s used. A)
Determi ne the coeffi ci ent of ki neti c fri cti on between the box and surface. B) The box i s turned on i ts si de so that hal f of
the
area of the box i s touchi n
g the tabl e, but sti l l onl y 49N of force i s needed to sl i de i t at a constant speed, determi ne the
coeffi ci ent of fri cti on. C) What does thi s i mpl y about the effect of surface area on the coeffi ci ent of fri cti on?




A



B










Answers


1a) 14.7 N

b) si nce Fnet=0, Fpush=Fk, so al so 14.7 N 2a) 1.55, b) 1.39,

3) a=3.38 m/s
2

(note: Fn=216.54, fk=65), 4) u=0.76 (note: Fn=42.53, fk=32.25)

5a) 197.8 N, 7) u = 0.5 for both answers, fk and Fn are the same i n each. Surface area does not affect u,

onl y surface type
does.


HW19B


Castle Learning



l og i n and compl ete the assi gnment



Intentional Blank Page



Physics HW #20













PAGE 1 of 2


HW20A


Probl ems Bel ow


1.) A 72 kg box sl i des down a 22° ramp. The coeffi ci ent of ki neti c fri cti on b
etween the box and the ramp i s 0.17. Determi ne the
accel erati on of the box as i t sl i des down the ramp.









2.) A gi rl on a sl ed starts from rest and coasts down a 50 degree i ncl i ned hi l l i n 2.5 seconds, reachi ng l evel ground at the
bottom
wi th a speed of 3.25 m/s. The gi rl and sl ed together wei gh 645 N. (a) Determi ne the accel erati on on the i ncl i ne, (b) Deter
mi ne
the coeffi ci ent of ki neti c fri cti on on thi s i ncl ine









3.) A 981 N ki d sl i des i n di rt wi th a coeffi ci ent of ki neti c fri cti on of 0.5 movi ng at an i ni ti al speed of 3.25 m/s and trave
l s an
unknown di stance unti l she comes to rest. Determi ne the
di stance the gi rl travel s on the fl at ground before comi ng to rest.












4.) A 2.8 kg steel bl ock on a 26° steel i ncl ine and i s pushed up the i ncl i ne at a constant speed wi th a force paral l el to the

l ength
of the i ncl i ne. Fi nd the force pushi n
g the bl ock up the i ncl i ne










5.) Graphi ng Questi on on next page



HW20B


Castle Learning
-

Logon to castl e l earni ng and compl ete the mul ti pl e choi ce questi ons



Answers


1) a=2.13 m/s
2
(fk=111.33, Fn=654.9), 2) use ki nemati cs, a=1.3m/s
2
,
u=0.985 (fk=408.5, Fn=414.6)

3) d = 1/08 m (a=4.91 m/s
2
), 4) Look up u on ref tabl e. F=26.11 N (const speed i s key, fk=14.07, Fn=24.7)



PAGE 2 of 2


5.) A box i s pl aced on an i ncl i ne and remai ns at rest as the angl e i s sl owl y i ncreased. The fri cti on for
ce and max
stati c fri cti on
force i s determi ned for each angl e i ncrease.


a)

In the tabl e, how i s the “fri cti on force” cal culated, show a sampl e
cal cul ati on for the fi rst val ue i n the tabl e (draw a FBD and use i t to thi nk about
how the actual stati c fri
cti on force acti ng i s found









b)

On the graph bel ow, pl ot both “fri cti on force vs
θ” and “fs(max) vs. θ” (two separate trend l i nes on the same graph).
Use some sort of l egend to di sti ngui sh each l i ne. Be sure to l eave some extra graph gri d spaces to t
he ri ght (meani ng
don’t use the whol e graph for your pl ot and l eave some bl ank space l eft over), l abel the axi s appropriatel y.

Fri cti on vs. Angl e















































































































































































































































































































































































































































































c)

Based on the graph above, esti mate the angl e at whi ch the box woul d sl i p, expl ai n how you di d i t





d)

Usi ng any of the val ues from the tabl e,

determi ne the val ue of µ
s
, show work.








Physics HW #21
, (No castl e l earni ng thi s ti me)









PAGE 1 of 1





This page may be turned instead

of loose leaf.

1.) Identi fy the force that mai ntai ns the ci rcul ar moti on of the fol l owi ng (meani ng i denti
fy whi ch force i s the centri petal force)


(a) A car roundi ng a curve on pavement





_________________________________


(b) A yo
-
yo swung i n a hori zontal ci rcle around someone’s head


_________________________________


(c) A boy sl i ding down a curved sl i de

at a water park




_________________________________


2.) An object moves i n a ci rcul ar path wi th constant speed, v.


(a) Is the objects vel oci ty constant, expl ai n.







(b) i s the objects accel erati on constant, expl ai n.








3.) Gi ve an exampl e
of a si tuati on i n whi ch an automobi l e dri ver can have a centri petal accel erati on but not tangenti al
accel erati on, expl ai n.








4.) Can a car move around a ci rcul ar track so that the car has a tangenti al accel erati on but no centri petal accel erati on, exp
l ain









5.) The gas pedal and the brakes of the car can cause accel erati on and decel erati on. Expl ai n how a steeri ng wheel can cause
accel erati on.











Intentional Blank Page



Physics HW #22













PAGE 1 of 2





HW22A Questions


1.)
When a rol l ercoaster goes around a l oop, what force provi des the centri petal force at the top of the l oop?


2.) Two coi ns are pl aced on a record and the record spi ns. The outsi de coi n i s twi ce as far from the center of the record
compared to the other coi
n, i s 3 ti mes as heavy as the i nsi de coi n and moves twi ce as fast as the i nsi de coi n. Numeri cal l y
compare the centri petal force on the outsi de coi n to the i nsi de coi n.


3.) A young boy swi ngs a yo
-
yo hori zontal l y above hi s head so that the yo
-
yo has a cen
tri petal accel erati on of 40 m/s
2
. If the yo
-
yo’s stri ng i s 0.5 m l ong, what i s the yo
-
yo’s tangenti al speed.


4.) A 900 kg test car travel s around a ci rcul ar track that has a l ength of 3.05 km (the ci rcumference of the track). If the
magni tude of the for
ce that mai ntai ns the car’s ci rcular moti on i s 2140 N, what i s the car’s tangenti al speed.


5.) A bui l di ng superi ntendent twi rl s a set of 200 g keys i n a hori zontal ci rcle at the end of a cord. If the keys have a cen
tri petal
accel erati on of 125 m/s
2

and t
he tangenti al speed of the keys i s 6.25 m/s, (a) how l ong i s the cord and (b) how much force must
the man pul l on the attached cord to keep the keys i n moti on?


6.) A 12000 N car travel i ng at 45 km/hr rounds a curve of radi us 180 m. Fi nd the fol l owi ng (a)

the centri petal accel erati on of the
car (b) the force that mai ntai ns the centri petal accel erati on (c) the mi ni mum coeffi ci ent of stati c fri cti on between the ti re
s and
the road that wi l l al low the car to round the curve safel y.


7.) The moon ci rcl es the ea
rth once i n 28 days at a radi al di stance as shown on the Regents reference tabl e. (a) Determi ne the
average speed of the moon i n i ts orbi t i n (m/s). (b) Determi ne the centri petal force acti ng on the moon (c) What force provi
des
the centri petal force foun
d i n part b


8.) A 1000 kg car travel s at constant speed around a secti on of hori zontal, ci rcular track. A) On the di agram, draw an arrow

at
poi nt P to represent the di recti on of the centri petal accel erati on of the car when i t i s at poi nt P. B) The radi us

of the track i s 20
m. a) If the car took 15 seconds to travel from start to end, determi ne the magni tude of the centri petal force at poi nt P. b
)
What speci fi c type of force provi des the centri petal force for the car.



9.) On next page


HW22B


castle l
earning online review problems




Answers



1) Fn, 2) 6x as much, 3) 4.47 m/s
, 4) 34 m/s, 5a) 0.3125 m, b) 25

N, 6a) 0.87, b) 1062 N, c) .09

7a) 997.3 m/s, b) 1.9x10
20

N, c) gravi ty, 8a) 878.8 N, b) stati c fri cti on
Questi on 9)












PAGE 2 of 2



In
an experi ment, a rubber stopper i s
attached to one end of a stri ng that i s passed
through a pl asti c tube before wei ghts are
attached to the other end. The stopper i s
whi rl ed i n a hori zontal ci rcul ar path at
constant speed.



(a) On the di agram of the top
vi ew

draw the path of the rubber stopper i f the stri ng
breaks at the posi ti on shown.






(b) Descri be what woul d happen to the radi us of the ci rcl e i f the student whi rl s the stopper at a greater speed wi thout chang
i ng
the bal anci ng wei ghts.





(c) Li st

three
measurements

(easi l y measureabl e quanti ti es) that must be taken to show that the magni tude of the centri petal
force i s equal to the bal anci ng wei ghts. [Negl ect fri cti on]







(d) The rubber stopper i s now whi rl ed i n a verti cal ci rcle at the same
speed. On the di agram draw and l abel vectors to i ndi cate
the di recti on of the wei ght (
Fg
) and the di recti on of the centri petal force (
Fc
) at the posi ti on shown.


















Physics HW #23












PAGE 1 of 1


HW23A

Questi ons

1.) Astronauts fl oati n
g around i nsi de the space shuttl e are not actual l y i n a zero
-
gravi ty envi ronment. What i s the real reason
astronauts seem wei ghtl ess, expl ai n ful l y.



2.) Descri be how satel l i tes are made to orbi t and be sure to i denti fy the force that provi des the
centri petal force to mai ntai n the
moti on.



3.) Two objects are a di stance d apart and experi ence a gravi tati onal force F. How much woul d the di stance need to change by
i n order to produce a gravi tati onal force 9 ti mes l arger than i t i ni ti ally was?



4.)

Two objects are a di stance d apart and experi ence a gravi tati onal force of 2000 N. If the mass of one of the objects was made

4 ti mes l arger and the di stance between the objects was made 3 ti mes smal l er what woul d the new force be?



5.) Two equal masses
are a di stance d apart and experi ence a gravi tati onal force F. The two masses are repl aced wi th di fferent
si ze masses (but sti l l equal to each other). The di stance between the two objects i s al so reduced to

¼ d and the resul ti ng Force i s now changed to
64 ti mes the ori gi nal val ue. By what factor were the masses changed by
compared to thei r ori gi nal value?



6.) A 90 kg person stands 2 m away from a 60 kg person si tti ng on a bench nearby. What i s the magni tude of the gravi tati onal

force between them?



7.) Mars has a mass of about 6.4 x 10
23

kg and i ts moon Phobos has a mass of about 9.6 x 10
15

kg. If the magni tude of the
gravi tati on force between the two bodi es i s 4.6 x 10
15
N, how far apart are Mars and Phoebos



8.) A person stands at the equator of
the earth, and i s therefore 1 earth radi i from the center. The earth rotates one ti me
around i n one day. Determi ne the speed of the person as seen from outer space, assume the earth i s a perfect ci rcl e.



9.) The peri od of the moons revol uti on i s 28 days
. Determi ne the speed of the moon around the earth assumi ng i ts orbi t i s
ci rcul ar.



10.) (a) Identi fy the speci fi c force that provi des the centri petal force to keep the Earth revol vi ng around the sun

(b) The earth takes 1 year to orbi t the sun, assume t
he orbi t i s a perfect ci rcl e and determi ne the speed of the earth i n i ts orbi t
(c) Cal cul ate the force that mai ntai ns the ci rcul ar moti on of the earth around the sun.



11.) A 1000 kg satel l i te i s i n a geosynchronous orbi t around an unknown pl anet that ha
s the same rotati on rate as the earth but
i s a di fferent si ze and mass. The satel l i te i s 35000 km above the center of the pl anet. (a) How fast must the satel l i te be m
ovi ng
to be i n thi s geosynchronous orbi t. (b) Cal cul ate the centri petal force acti ng on t
he satel l i te. (c) Usi ng your answer from b (and
knowi ng the speci fi c force that thi s centri petal force represents), determi ne the mass of the pl anet.


HW23B



Castl e Learni ng onl i ne probl ems


Answers



1) free fal l i ng, 2) F
G

= F
net(c),
3) 1/3 x, 4) F
i ncrease by 36x, so new F =72000 N, 5) si nce m
2
=4 when subbi ng i n numbers,
each mass must have been doubl ed, 6) 9x10
-
8

N, 7) 9.44x10
6

N, 8) 463.24 m/s, 9) 997.33 m/s, 10) gravi ty, 29886 m/s, 3.56x10
22

N, 11) 2545.27 m/s, 185.1 N, 3.4x10
24

kg



Physics HW #24










Page 1 of 1



HW 24A
-

Questions


1.) For each exampl e bel ow, i ndi cate whether the work done on the second object wi l l have a posi ti ve, negati ve or zero val ue.


(a) The road exerts a fri cti on force on a speedi ng car ski ddi ng to a s
top

(b) A rope exerts a force on a bucket as the bucket i s rai sed up a wel l

(c) Ai r exerts a force on a parachute as the parachuti st sl owl y falls to Earth

(d) A man pushes on a stati onary wal l.


2.) If 2.15 J of work i s done by a person l i fti ng a 160

g appl e at a constant speed, how far i s i t l i fted


3.) A worker pushes a 1.25x10
3

N crate hori zontal l y wi th a force of 500 N @ 30 degrees bel ow the hori zontal, and he moves i t a
di stance of 24 m. The coeffi ci ent of ki neti c fri cti on between the crate and
the fl oor i s 0.10

(a) How much work i s done by the worker on the crate

(b) How much work i s done by fri cti on on the crate

(c) How much work i s done by gravi ty

(d) What i s the net work done on the crate


4.) A car wi th a mass of 2.5x10
3

kg starts from rest and accel erates to a speed of 16.5 m/s i n 11.5 sec as i t i s pushed hori zontal l y
by the force of the car’s engi ne. Assume that the force of resi stance (fri cti on, ai r resi stance) against the moti on of the c
ar
remai ns constant at 400 N d
uri ng thi s ti me. (a) What i s the accel erati on of the car (b) What i s the force of the engi ne (c) What i s
the average power of the car engi ne.


5.) A harri er jet pl ane i s desi gned for verti cal takeoff and has a mass of 8x10
3

kg. Fi nd the net work done on t
he pl ane as i t
accel erates upward at 0.9 m/s
2

through a di stance of 30 m after starti ng from rest.


6.) A car at rest has a 144 kW engi ne operate for 1.8 mi nutes to bri ng i t to a fi nal speed of 5 m/s.


(a) How much force di d the engi ne exert on the car.


(b) How much work was done on the car.


7.) A constant force of 20 N acts on a box. The box i s movi ng at a constant speed of 3.7 m/s. (a) How much work i s done by t
he
force i n 6 seconds? (b) How much net work i s done?


8.) A 10.
-
ki l ogram bl ock i s pushed a
cross a fl oor by a hori zontal force of 50. newtons. The bl ock moves from poi nt A to poi nt B i n
3.0 seconds.




a)

Usi ng a scal e of 1.0 centi meter = 2 meters, determi ne the magni tude of the di spl acement of the bl ock as i t

moves from poi nt A to poi nt B


b)

Cal cul ate the power requi red to move the bl ock from poi nt A to poi nt B i n 3.0 seconds.



HW24 B


Castle Learning Problems



Answers


1)

-
, +,
-
, 0
2)

1.37 m,
3)

+ 10392.3 J,
-
3600 J, 0, 6792.3 J,
4)

1.435 m/s
2
, 3975 N, 32800 W,

5)

216000 J,
6)

57600 N, 1.56x10
7

J,
7)

444 J, 0,
8)

measure


16.3 m, 271.67 W



Physics HW #25











Page 1 of 2



HW25A Questions



1.) A car has a ki neti c energy of 4.32x10
5

J when travel i ng at a speed of
18

m/s. (a) What i s i ts mass? (b) How fast woul d a 10 kg
bowl i ng bal l have to travel to have the same energy as the car.


2.) A pi nbal l bangs agai nst a bumper gi vi ng the bal l a speed of
26

cm/s. If the bal l has a mass of
40

g, what i s the bal l s ki neti c
energy i n joul es.


3.) A spoon i s rai sed
15

cm above a tabl e. If the spoon and i ts contents have a mass of
28

g, what i s the gravi tati onal potenti al
energy associ ated wi th the s
poon at that hei ght rel ati ve to the tabl e surface.


4.) A 75 kg skydi ver i s
850

m above the earth’s surface movi ng at
36

m/s. What i s the mechani cal energy of the skydi ver at thi s
poi nt (express your answer i n sci enti fi c notati on).


5.) A spri ng l yi ng hori zontal ly at rest has a l ength of 1m. A
9.5

N force hol ds the spri ng at a new l ength of
1.20

m. What i s the
el asti c energy i n the spri ng?


6.) A spri ng wi th a spri ng constant of
100

N/m i s attached to the cei l i ng and a
5

kg mass i s attached to i t. The stretched l ength
of the spri ng

i s measured to be 1.75 m. What i s the rel axed l ength of the spri ng.


7.) A 25 cm l ong spri ng wi th a force constant of
1.7

N/m i s si tti ng on the ground i n a verti cal posi ti on. A mass i s pl aced on top of
the spri ng and i t compresses i t

10 cm. (a) Fi nd the Force i n the spri ng, (b) Fi nd the val ue of the mass pl aced on the spri ng , (c)
fi nd the el asti c energy i n the spri ng


8.) A
10

cm l ong spri ng wi th a spri ng constant of
45

N/m rests hori zontal l y
and i s stretched to a new l ength of 60 cm. Cal cul ate
the el asti c potenti al energy i n the spri ng


9.) The graph bel ow, represents the rel ati onship between verti cal hei ght and gravi tati onal potenti al energy for an object nea
r
Earth’s surface. (The same gr
aph appears i n your answer
bookl et.)


a) Based on the graph, what i s the gravi tati onal potential
energy of the object when i t i s 2.25 meters above the
surface of Earth?


b) Usi ng the graph, cal cul ate the mass of the object.


c) What physi cal quanti ty doe
s the sl ope of the graph
represent?


d) Usi ng a strai ghtedge, draw a l i ne on the graph i n your
answer bookl et to represent the rel ati onshi p between
gravi tati onal potenti al energy and verti cal hei ght for an
object havi ng a greater mass.







Page 2 of 2



10.) A student performed an experi ment i n whi ch the wei ght attached to a suspended spri ng was vari ed and the resul ti ng total
l ength of the spri ng measured. The data for the experi ment are i n the tabl e bel ow.




a) Usi ng the i nformati on i n the data
tabl e, construct a graph, fol l owi ng the di recti ons bel ow.

-

Pl ot the data poi nts for the attached wei ght versus total spri ng l ength.

-

Label and ti tl e your graph appropri atel y wi th uni ts.


-

Draw the l i ne or curve of best fi t.







b) Usi ng your graph, determi ne the l ength of the spri ng before any wei ght was attached.

c) Usi ng your graph, determi ne the spri ng constant of the spri ng


HW25B


Castle Learning



ANSWERS


1a)
2666.7 kg,
b)

293.94 m/s,
2)

0.00135 J,
3)

0.0412 J,
4)

674000 J,
5)

0.95 J, m,

6)

1.26 m,
7a)

0.17 N,
b)

0.017 kg,
c)

0.0085 J,
8)

5.625 J,
9)

55J, 2.49 kg, wei ght, l i near but sl i ghtl y more sl ope,
10)

be sure
i t’s a best fi t l i near l i ne, rel axed l ength: extend l i ne to x axi s = 0.29 m, k = sl ope =

13.69 N/m

A

B

C

2/3 h

h


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Physics HW #26










Page 1 of 2



HW26A Questions



1.) A
100

gram

marbl e rol l s on the fri cti onl ess
track shown starti ng from a hei ght of h =
26

cm as shown bel ow. The bal l i s rel eased from
rest at A. Cal cul ate (a) the speed at B (c) the
speed at poi nt C








2.) A
40

kg pol e vaul ter

runs on the ground at 10 m/s and vaul ts over a bar of
unknown hei ght. The vel oci ty when the runner goes over the bar i s 2 m/s.
Ignori ng ai r resi stance, how hi gh i s the bar?




3.) A
2600

N box sl i des across a tabl e wi th a coeffi ci ent of ki neti c fri cti on of
0.25 and i t comes to rest after travel i ng
26

m. (a) How much work i s done by
fri cti on (b) What i s the change i n energy of the box as i t sl i des across the
surface.

(c) What i s the i ni ti al speed of the box



4.) A hori zontal spri ng wi th a force constant (spri ng constant) of 80 N/m i s
compressed on a fri cti onl ess surface, a di stance of
9.5

cm from i ts rel axed
l ength. A
36

g box i s pl aced next to i t and i s rel eased. What wi l l the speed of
the box be when the spri ng reaches i ts rel axed l ength and the box l eaves the
spri ng?


5.) A hori zontal BB gun,

2.25

m off the ground, fi res a pebbl e of mass m at a
hori zontal vel oci ty of
5

m/s. (a) Use energy conservati on to determi ne the
speed of the BB when i t hi ts the ground (b) Use projecti l e methods to
determi ne ho
w far away the bal l l anded from the shooter.


6.) A
9.5

g bul l et movi ng at
360

m/s penetrates a tree trunk to a depth of
36

cm
unti l fri cti on from the tree has stopped i t. Use work energy consi derati ons to
fi nd the magni tude of the force that stops the bul l et


7.) A
1.5

kg box sl i ding on a fri cti onl ess surface at
3

m/s hi ts a 50 cm l ong
hori zontal spri ng and compresses i t by
10

cm unti l i t comes to rest. (a)
Determi ne the spri ng constant of the spri ng. (b) How much work i s done

by the
spri ng to stop the box


8.) An
average

force of 50 N i s needed to compress a spri ng 5 cm. How much el asti c energy i s stored i n the spri ng.


9.) A spri ng was compressed 5 cm by a vari able force and hel d i n pl ace by a 50 N force, how much el asti c
energy woul d be
stored i n the spri ng.


10.) A box at the top of a rough i ncl ine possesses 981 joul es of gravi tati onal potenti al energy compared to the bottom of the

i ncl i ne. As the box sl i des to the bottom of the i ncl ine, 245 joul es of heat i s produced. D
etermi ne the ki neti c energy of the box at
the bottom of the i ncl i ne.


11.) A 10 kg box movi ng wi th a ki neti c energy of 500 J sl i des across a rough patch. It moves across the patch and emerges at

a
speed of 8 m/s. (a) How much i nternal

energy i s generated as the box moves across the patch (b) If the coeffi ci ent of ki neti c
fri cti on was 0.4, how l ong was the rough patch?
d
X

2600

N


V
F
=0


/
\
/
\
/
\
/
\
/
\
/
\
/
\
/
\
/
\
/
\
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\


d
Y


/
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/
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/
\
/
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/
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/
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/
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/
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/
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\

12.) A spri ng wi th a spri ng constant of 40 newtons per meter i s compressed by a force




Page 2 of 2


of 30 newtons. W
hat i s the total el asti c potenti al energy stored i n thi s compressed spri ng?


13.) Usi ng the graph, determi ne the total work done i n
movi ng the box 6.0 meters?












14.) The graph bel ow represents the moti on of a 5
gram

marbl e movi ng on a rol l ercoaster track.
Note that the scale on the y
axis has units x 10
-
4

(therefore the “20” on the y axis is actually 20 x 10
-
4

J).


a) From the graph, by how much does the mechani cal energy change over the course of the tri p


b) What
i s most l i kel y the cause of thi s l oss of mechani cal energy, and where does the energy go


c) What i s the speed of the marbl e at 0.4 sec? (thi s about whi ch energy you can use to get speed)


d) What i s the maxi mum hei ght of the marbl e? (thi nk about whi ch ene
rgy you can use to get hei ght and



where on the graph the l argest amount i s)



HW26B


Castle Learning


Answers:

1a)

2.26 m/s,
b)

1.3 m/s,
2)

4.89 m,
3a)

-
16900 J,
b)

-
16900 J,
c)

11.29 m/s,
4)

4.47 m/s,

5a)

8.32 m/s,
b)

3.39 m,
6)

1710 N,
7a)

1350 N/m,
b)

6.75 J,
8)

2.5 J,
9)

1.25J,
10)

736 J,
11a)

180J,
b)

4.59 m,
12)

11.25 J,
13)

27 J,
14a)

30x10
-
4
J,
b)

fri cti on, i nternal energy,
c)

1.67 m/s,
d)

0.31

m

180 x10
-
4


160 x10
-
4


140 x10
-
4


120 x10
-
4


100 x10
-
4


80 x10
-
4


60 x10
-
4



40 x10
-
4


20 x10
-
4



Physics HW #28










Page 1 of 1



HW28A Questions


1.) The speed of a parti cl e i s doubl ed (a) by what factor i s i ts momentum changed (b) What happens to i ts ki neti c energy


2.) When a force i s exerted
on an object, does a l arge force al ways produce a l arger change i n the object’s momentum than a
smal l er force does, expl ai n


3.) What i s the rel ati onshi p between i mpul se and momentum


4.) A truck l oaded wi th sand i s movi ng down the hi ghway i n a strai ght pa
te (a) What happens to the momentum of the truck i f
the truck’s vel oci ty i s i ncreasing. (b) What happens to the momentum of the truck i f sand l eaks at a constant rate through a

hol e i n the truck bed whi l e the truck mai ntai ns a constant vel oci ty. Expl ai n

answers.


5.) When a car col l i sion occurs, an ai r bag i s i nflated, protecti ng the passenger from seri ous i njury. How does the ai r bag
soften
the bl ow? Use physi cs terms i nvol ved wi th i mpul se and momentum to expl ai n.


6.) If you jump from a tabl e onto th
e fl oor, are you more l i kel y to be hurt i f your l egs are rel axed or sti ff and your knees are
l ocked? Use physi cs terms i nvol ved wi th i mpul se and momentum to expl ai n.


7.) A
0.40

kg soccer bal l approaches a pl ayer hori zontal ly wi th a vel oci ty of
10

m/s to the north. The pl ayer stri kes the bal l and
causes i t to move i n the opposi te di recti on wi th a vel oci ty of
13

m/s. What i mpul se was del i ve
red to the bal l by the pl ayer?


8.) A
4.7

kg bal l stri kes the wal l wi th a vel oci ty of 8.5 m/s to the l eft. The bal l bounces off wi th a vel oci ty of 7.5 m/s to the ri gh
t.
If the bal l i s i n contact wi th the wal l for
0.10

sec, what i s the constant force exerted on the bal l by the wal l?


9.) A
14

g basebal l movi ng at +
22

m/s i s sl owed to a stop by a catcher who exerts a constant force of
300

N i n a di recti on
opp
osi te the moti on of the bal l. (a) How l ong does i t take thi s force to stop the bal l? (b) How far does the bal l si nk i nto the
catchers mi tt before stoppi ng?


10.) A
51

kg pol e
-
vaul ter fal l s from rest from a hei ght of
4

m onto a foam
-
rubber pad. After fal l i ng the 4 m, the pol e vaul ter
then hi ts the mat and i s i n brought to rest whi l e i n contact wi th the mat for 0.3 seconds. (a) Cal cul ate the athl ete’s vel oc
i ty just
before reachi ng the pad (b) Cal cul ate the net force

acti ng on the vaul ter whi l e he i s bei ng brought to rest by the mat . (Note,
there are two parts, the fal l and then the part where the man si nks i nto the pad).


11.) A 1000
-
ki l ogram car travel i ng due east at 15 meters per second i s hi t from behi nd and recei ves a forward i mpul se of 6000
newton
-
seconds. Determi ne the magni tude of the car’s change i n momentum due to thi s i mpul se.


12.) A car wi th mass m possesses mo
mentum of magni tude p. Whi ch expressi on correctl y represents the ki neti c energy, KE, of
the car i n terms of m and p?



HW28B


Castle Learning (online)



Answers:

1) a) x2, b) x4, 2) No, ti me matters al so, J=Δp=Ft, 3) J=Δp, 4) based on p=mv

… a) p i nc., b) p dec, 5) more t


l ess

F,
6) sti ff, l ess t


more F, 7) 9.2 Ns South, 8) 752 N ri ght, 9a) 0.001 sec, b)0.0113 m,

10a) 8.86 m/s, b) 1506.2 N, 11) 6000 kg m/s, 12) sub i n p=mv and cancel m to get choi ce 4.



Physics HW #29










Page 1 of 1




HW 29A Questions

1.) Two skaters on i ce are faci ng each other touchi ng and i ni ti ally push agai nst each other so that they move i n opposi te
di recti ons. What i s the total momentum of the two skaters when they begi n movi ng? Expl ai n your answ
er.


2.) An astronaut carryi ng a camera i n space fi nds hersel f dri fti ng away from a space shuttl e after her tether strap becomes
unfastened. If she has no propul si on devi ce, what shoul d she do to move back to the shuttl e?


3.) Gi ven the masses of two obje
cts and thei r vel oci ti es before and after a head on col l ision, how coul d you determi ne whether
the col l i sion was el astic, i nel astic, or perfectl y i nel asti c? Expl ain and refer to how you woul d use the vel oci ti es gi ven to

fi nd the
answer.


4.) A person on a

2.1

kg skateboard i ni ti ally at rest tosses a
6.5

kg jug of water i n the forward di recti on. If the jug has a speed of
4

m/s rel ati ve the ground and the person and skateboard move i n the opposi te di recti on at 0.60 m/s, fi nd the person’s mass.


5.) A
1.2

kg skateboard i s coasti ng al ong the pavement at a speed of
4.5

m/s when a 0.80 kg
cat drops from a tree verti cal l y onto
the skateboard. What i s the speed of the skateboard
-
cat combi nati on.


6.) A 150 g toy car movi ng to the ri ght at 35 cm/s has a col l i sion wi th a 200 g toy car movi ng i n the opposi te di recti on at 3
0 cm/s.
After col l idi
ng, the 150 g car moves wi th a vel oci ty of 7.1 cm/s to the l eft. Fi nd the vel oci ty of the 200 g car after the col l i sion, i n
cm/s, and determi ne what type of col l i sion thi s i s (show work and expl ai n answer).


7.) A tenni s pl ayer pl aces a
5
2

kg bal l machi ne on a fri cti onl ess surface. The machi ne fi res a 57 g tenni s bal l hori zontally wi th a
vel oci ty of
32

m/s towards the north. What i s the fi nal vel oci ty of the machi ne


8.) A 50
-
ki l ogram chi l d running at 6.0 meters pe
r second jumps onto a stati onary 10.
-
ki logram sl ed. The sl ed i s on a l evel
fri cti onl ess surface. a) Cal cul ate the speed of the sl ed wi th the chi l d after she jumps onto the sl ed. b) Cal cul ate the ki ne
ti c
energy of the sl ed wi th the chi l d after she jumps on
to the sl ed. c) After a short ti me, the sl ed reaches a rough l evel surface that
exerts a constant fri cti onal force of 54 newtons on the sl ed. How much work must be done by fri cti on to bri ng the sl ed wi th t
he
chi l d to a stop?


9.) A 1200
-
ki l ogram car
movi ng at 12 meters per second col l ides wi th a 2300
-
ki l ogram car that i s wai ti ng at rest at a traffi c l i ght.
After the col l i sion, the cars l ock together and sl i de. Eventual l y, the combi ned cars are brought to rest by a force of ki neti
c
fri cti on as the rubb
er ti res sl i de across the dry, l evel, asphal t road surface.

a) Cal cul ate the speed of the l ocked
-
together cars i mmedi atel y after the col l i sion. b) Cal cul ate the magni tude of the fri cti onal
force that bri ngs the l ocked
-
together cars to rest. c) Cal cul ate t
he di stance over whi ch the fri cti onal force acted to bri ng the
l ocked
-
together cars to rest.


10.) A 4.0
-
ki l ogram cart movi ng to the ri ght at 3 m/s and a 6.0
-
ki l ogram cart movi ng to the l eft at 3 m/s on a hori zontal
fri cti onl ess surface col l ide wi th each
other and they l ock together. Determi ne the magni tude of the total momentum of the two
-
cart system after the col l i sion.


11.) Two masses col l ide as shown. Before the col l i sion, mass m
A

i s movi ng to
the ri ght wi th speed v, and mass m
B

i s at rest. Upon col l i sion, the two masses
sti ck together. Whi ch expressi on represents the speed, v', of the masses after
the col l i sion?




HW29B


Castle Learning (online)


Answers:

1) zero, + and


cancel, 2) throw camera i n di recti on away from shi
p, 3) method gi ven i n notes,

4) 41.23 kg, 5) 2.7 m/s, 6) 1.58 cm/s, KEi =0.0182 J KEf = 0.0029 J … i nel asti c since not equal, 7) 0.035 m/s, 8) 5 m/
s, 750 J,
-
750 J, 9a) 4.11 m/s, b) 23000 N, c) 1.29 m, 10)
-
6 kg m/s, 11) choi ce 4.