# Week 6

Urban and Civil

Nov 29, 2013 (4 years and 5 months ago)

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TURBO TAKS

Week 6

Lesson 1: Body Systems

Lesson 2: Heat Transfer & Waves

Lesson 3: Energy & Electricity

Lesson 4: Motion, Forces, & Physics Equations

Lesson 1:

Body Systems

The Human Body

must also
maintain
homeostasis (a
balance).

The organs of the
body work together in organ
systems to perform specific
functions.

Organ systems are often
connected

and work
together to allow the body
to function.

Integumentary:

Skin, hair, nails:
Protects, prevents infection,
temperature control

Skeletal

Support and protection
of organs.

Muscular

Uses bones as simple
machines to exert force on the
body to create movement.

Nervous

Control system of the
body. Works with other
systems to maintain
homeostasis.

Endocrine

Secretes hormones
that circulate in the blood
stream and tell other systems
what to do.

Reproductive:

produces
gametes in ovaries and testis.

Circulatory:

transports
oxygen and nutrients to
cells and removes wastes.

Respiratory

Brings O
2

to
circulatory system and removes
CO
2

(gas exchange!).

Immune

Fights infection

Helper T
-
cells and macrophages turn
on the immune response and start
.

Digestive:

breaks down
food and absorbs
nutrients

Excretory

Takes waste
from the blood stream for
removal from the body.

Lesson 2: Heat Transfer and
Waves

Heat Transfers

Heat moves from hot to cold.

Example: When you put your hand on a
lab table it feels cold because the heat in
transferring down, into the table. Not the
other way around.

Heat from the 25
o
C block is sinking into the
10
o
C block

Heat does not rise, hot air rises.

10
o
C

25
o
C

Conduction

Conduction transfers from one substance to
another by
direct contact
of molecules.

THINK: Solids

Example: When you touch a hot stove!

25
o
C

5
o
C

slow transfer

wood

25
o
C

5
o
C

fast transfer

metal

Convection

Convection transfers heat through moving currents in
fluids (gases or liquids). Convection cannot occur in
solids, because solids can’t move.

THINK: Liquids and Gases

Hot liquids (and
gases) are less dense
and rise, causing
convection currents
.
These currents
transfer heat
throughout the
liquid (or gas).

Heat Source

Hot

Liquid
Rises

cooler

liquid

falls

cooler

liquid

falls

Much of the weather on earth
comes from convection currents.
The sun warms air at the surface
of the earth. Warm air rises,
causing winds. When the air
cools it falls back to the ground.

Hot air rises

Cold air is pulled in
from the sides

causing wind.

wind

wind

warm
ground

sunshine

Much of the
weather on earth
comes from
convection
currents. The sun
warms air at the
surface of the
earth. Warm air
rises, causing
winds. When the
air cools it falls
back to the ground

Examples:

Warmth you feel sitting

close to a campfire.

heat through

electromagnetic waves

pure thermal energy.

All energy on earth comes
originally from the sun. Only
vacuum of space to the earth.

Heat (thermal energy) in the form of
electromagnetic radiation from a light source.

Lets Practice

Name the type of heat transfer:

1.
Boiling water in a pot.

20
º
C

20
º
C

30
º
C

40
º
C

A

B

D

C

CONVECTION

3. McDonalds keeping french fries

warm under a heat lamp.

CONDUCTION

2. Your feet burning on concrete in the Summer time.

4. Which letter represents

a possible heat transfer?

D

(Always
hot
.

cold)

Waves

A wave is any disturbance that transmits
energy through matter or space

Types of Waves

1.

2.

Types of Waves

1. Compression/ Longitudinal wave

Produced by moving a slinky spring back and
forth.

Example: Sound

Types of Waves

2. Transverse Wave

Produced by waving

a rope or other medium

up and down

Example: Light wave, or a ripple in a pond

Parts of a Transverse Wave

Characteristics of All Waves

Wavelength
-

distance from a point in a wave to
the next point on the next wave in the same phase

Frequency
-

the number of times that a repeated
event occurs per second

For sound, High pitch

= high frequency

V = f
λ

(Velocity = frequency x wavelength)

Short Wavelength = High
Frequency

Long Wavelength = Low
Frequency

Wave Properties

Reflection

When waves bounce
off a hard boundary.

The sound waves are
bouncing off the tank.
(i.e.
-

mirror, echo)

Refraction

The bending of light as it passes from
one medium into another. (i.e.
-

lenses)

Wave Properties

Diffraction

Occurs when a wave bends
around a corner.

Interference

A wave

interaction that

occurs when

two or more

waves overlap.

Wave Properties

Resonance

Occurs when one object vibrates because of
another object’s vibrations.

Common in tuning forks and other musical
instruments

Example: Ear

hearing

Body of guitar vibrates

because of it’s strings

vibration.

Make sure sound is turned down.

Lets Practice

Diffraction, Interference, or Resonance.

1. Lenses

2. Using a mirror

3. Water waves passing
through an opening.

4. When the

primary colors of
light combine to
form white light

5. When singing
near a piano, the
keys can start to
sound.

REFRACTION

REFLECTION

DIFFRACTION

INTERFERENCE

RESONANCE

Lesson 3: Energy and
Electricity

Energy

Energy is the ability to cause motion or forces; the
units of energy are
joules (J).

Potential Energy

1.
Gravitational Potential Energy

(in Joules, J) is
stored energy, because an object is above the ground.

More height = more Potential Energy. It has the
potential

to cause motion and forces.

Gravitational Potential Energy= mass x
gravity

x height

E
p

= mgh

Potential energy equals

mass times gravity times height.

Potential

Energy

(
in
Joules
)

mass (
in
kilograms
)

height (
in
meters
)

acceleration due to
gravity (
9.8 m/s
2
)

Potential Energy

The acceleration due to
gravity

we
experience on Earth is 9.8 m/s
2
. In
space, gravity is 0 m/s
2
.

Potential Energy Practice: PE=mgh

Don’t forget
to use the
given
constants and
formulas!

Ex: How much potential energy does a 4 kg object have that
is 5 meters off the ground?

E
p

= mgh

E
p

= (4)(10)(5)

= (40)(5)

= 200 Joules

takes 5,000 J of energy)

m = 4 kg

h = 5 m

g = 10 m/s
2

E
p

= ?

m =

h =

g =

E
p

=

Kinetic Energy

Kinetic Energy

(in Joules, J) is the energy of
motion. Moving objects have kinetic energy.

Kinetic Energy=
½

mass x velocity
2

Mass is measured in kilograms (kg) and velocity is
measured in meters/second (m/s).

E
k

= (
½)
mv
2

Kinetic energy equals one
-
half

Times mass times velocity squared.

Kinetic

Energy

(
in
Joules
)

mass (
in

kilograms
)

velocity (in
m/s
)

Energy Transfers

Work

(in Joules, J) is
how forces change
energy.

Work=
Force x Distance

Power

(in Watts, W)
is how fast work is
done.

Power =
Work

Time

W = Fd

Work

(in
Joules)

Force (in
Newtons)

Distance (in
meters)

P = W/T

Power

(in
Watts)

Work (in
Joules)

Time (in
seconds)

Energy can be transferred from one type to another.

Efficiency

(in %)

Energy gained by

the object (in J)

Energy you tried to give

the object (in J)

x100
out
in
W
Eff
W

Efficiency

Efficiency

is the percentage of energy retained (not
lost) in an energy transfer.

Efficiency Calculation

Work In:

Work Out:

How much
energy you tried to
give
to the object thru an energy
transfer or work.

How much
energy
is
actually
gained
by the object
(how much it got out).

Here work is done on
the object, pulling it
up the ramp. This is
the total energy that
you tried to give the
object.

Work put
in 240 J.

2 m

After

10
kg

The object
only

got out 200 J.

x100
x100
200 J
x100
240 J
.83 x 100
= 83%
out
in
p
W
Eff
W
E
Eff
W

W
in
=Fd=
30(8)=240 J

W
out
=Ep
gained
=mgh
=10(9.8)2
=98(2)

= 196J

196

.82 x 100

=82%

Types of Energy

Thermal Energy

Heat
energy. A product of most
other forms of energy.

Mechanical Energy

Any
kind of Kinetic (moving) or
Potential (height) Energy.

Chemical Energy

Stored in
chemical bonds. Includes
energy in food, plants, and
batteries (produce electricity

by combining chemicals).

Electrical Energy

Energy of
moving electrons: lightening,
electricity.

Light energy
from light bulbs or the sun
(renewable solar energy).

Nuclear Energy

Energy from
makes huge amounts of energy,
but also long
-
waste like power plants.

Lets Practice

WORD BANK

a)

Kinetic Energy

b)
Potential Energy

c)
Energy

d)
Height

e)
Joules

Match with the terms to the right:

1.
The units for energy.

2.
The ability to create forces or motion.

3.
Energy because of an object’s motion.

4.
Energy because of an object’s position above
the ground due to gravity.

5.
Vertical distance above the ground.

Electricity

Moving of electrons through conductors.
The path must be closed, or electrons
cannot move.

Electrical Circuits

Series Circuit

Provides a single
conducting pathway
without junctions.

Parallel Circuit

When two or more components of
a circuit are connected across
junctions, providing separate
pathways for the current.

Which type of circuit would you rather have for your Christmas lights?

Parallel, so that if one light burns out, the current can still reach
the other bulbs.

Assuming the chart contains all energy transformations in the
Earth system, how much solar radiation

goes toward evaporating water?

F

40,000 terajoules

G

92,410 terajoules

H

121,410 terajoules

J

133,410 terajoules

Subtract all the energy
expenditures from the
total amount reaching
Earth.

173,410

52,000
-

81,000

370

40 = 40,000

Lesson 4: Motion, Forces, and
Physics Equations

Speed and Velocity

Speed

is the distance an object travels per
second.

Velocity

includes the
speed

of an object and
the
direction

of its motion.

They share a formula on your equation sheet.

d

s

t

Speed equals the distanced traveled

divided by the time it took to move that
distance.

Distance travelled

(
in meters
)

Time

(
in seconds
)

Speed

(
in
meter/sec
)

v =

d

t

Measuring Speed

To measure speed you must determine the
distance traveled and the elapsed time.

Initial Position

Final Position

25 m

Distance Traveled

0:05.0

Elapsed Time

5 sec

0:00.0

25m
5m/s
5sec
D
S
T

  

Acceleration

a
=

Acceleration equal change of velocity

divided by change of time
.

Change of
Velocity

(in meters/sec)

Change of
Time

(in seconds)

Acceleration

(in m/s
2
)

, so,
final initial
final initial
V V
V V V a
T

   

a =

a =

Δ
V

Δ
T

An object accelerates when it changes speed OR changes
direction!

If acceleration is unknown use acceleration due to
gravity out of the constants box on the formula chart!

Acceleration

is how fast you change velocity OR how much the
velocity changed in a certain amount of time.

Solving for Acceleration

1. Calculate initial velocity

8m
1sec
8m/s
f
final
D
V
T
V

 

4m
1sec
4m/s
i
initial
D
V
T
V

 

2
8 4
2
4
2m/s
2
f i
initial
V V
a
T
V

 

 
Accelerates for
2 seconds

4 m

Measure V
f

(Final Velocity)

8 m

Measure V
i

(Initial Velocity)

Measure
Δ
T

(Time it took to
Accelerate)

0.0

1.0

3.0

4.0

3. Determine the change in time.

2. Calculate final velocity

4. Plug into acceleration equation.

So
Δ
T = 2 sec

MOMENTUM

Momentum

is how hard it is to stop something and is a
product of an object’s mass and its velocity. Momentum
is increased if either the mass or velocity is increased.

p =
mv

Mass (in kg)

Velocity (in m/sec)

Momentum

(in
kgm
/sec)

Momentum equals
mass times velocity
.

Momentum

The canon ball has a
smaller mass and a larger
velocity. The canon has a
larger mass and a smaller
velocity. However, since
the system started with a
net momentum of zero,
the momentums of the
objects afterwards must
be equal and opposite to
cancel each other out,

or = 0.

P
canon

= P
canon ball

Forces

A
force

is a push or pull that one body exerts
on another. Force is measured in Newtons (N).

15 N

65 N

10 kg

Total Net Force

= +65
-
15

= 50 N

Right is positive.

Left is negative.

Newton’s Laws of Motion:

1.
An object in motion will stay
in motion unless a force acts
upon it. (Law of Inertia). If
an object is at rest, it will
stay at rest until acted upon.

*Why we need seatbelts.

2.
Force = mass x acceleration

*Why a bowling ball does not
go as fast as a ping pong ball
when the same force is
applied.

3. For every action there is an
equal and opposite reaction.

*Why a rocket goes up when
gasses push down.

Inertia

Inertia is the tendency to not change
motion, and is dependent only on the
object’s mass (measured in kilograms).

-

Newton’s First Law.

Object’s with more

mass have more inertia
and are harder to push.

Object’s with less

mass have less inertia

and are easier to push.

Frequent Equations from the Formula Sheet

Solving Physics Problems:

1.
Identify what is being asked and

underline

or
highlight

it.

2.
Find the appropriate formula and
write it
down

3.
Plug in the
known

information

(
WRITE IT OUT
).

4.
Solve

for the unknown.

Lets Practice the Steps Together…

What is the approximate difference in
gravitational potential energy

of a 2kg
object 3m off the ground and a 2kg object
1m off the ground?

F) 19J

G) 39 J

H) 59 J

J) 79 J

First Situation

PE=mgh

PE=(2)(9.8)(3)

PE= 58.8 J

Second Situation

PE=mgh

PE=(2)(9.8)(1)

PE= 19.6 J

Difference Between=

58.8

19.6 = 39.2 J

or approximately

39J = G

gravitational potential energy

The illustration above shows a student about to throw a ball while
standing on a skateboard. Which illustration below correctly shows the
skateboard’s direction of motion after the student releases the ball?

A

B

C

D

skateboard’s direction of motion

A cyclist moves at a constant speed of 5
m/s. If the cyclist does not accelerate during
the next 20 seconds, he will travel

A 0 m

B 4 m

C 50 m

D 100 m

and giving us speed and time.

S=d/t

5=d/20

(Multiply by 20 on each

side of the equal sign.)

20 x 5= 100m = D

How much work is performed when a 50 kg
crate is pushed 15 m with a force of 20 N?

F

300 J

G

750 J

H

1,000 J

J

15,000 J

work

W=Fd

W= (20)(15)

W= 300 J = F

Watch out for extra information!

Levers

Which lever arrangement requires the least
effort force to raise a 500 N resistance?

A mechanic used a hydraulic lift to raise a

12,054 N car 1.89 m above the floor of a

garage. It took 4.75 s to raise the car. What

was the power output of the lift?

A) 489 W

B) 1815 W

C) 4796 W

D) 30,294 W

This is a two part calculation.

You’re looking for Power, but must have
work before you can solve (P=w/t)

1.
Calculate work:

w=fd

w=(12054)(1.89)

w=22,782.06 J

2. Calculate power:

P=w/t

p=(
22,782.06
)

(4.75)

P=4796.22 W

We know it’s a force because it’s
measured in Newtons!

A ball moving at 30 m/s has a momentum
of 15 kg∙m/s. The mass of the ball is

A

45 kg

B

15 kg

C

2.0 kg

D

0.5 kg

momentum

Momentum = mass x velocity

P=mv

15=m(30)

Divide by thirty on both sides.

15/30= 0.5 kg = D