Kinematic Equations - jflaherty1@kleinisd.net

filercaliforniaMechanics

Nov 14, 2013 (3 years and 11 months ago)

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Kinematics

Day 3

Kinematic Equations


Used in
situations
with uniform
acceleration

2 2
2
/
2
1
2
f i
f i
i
V d t
V V at
V V ad
d Vt at

 
 
 
Kinematic Equations
-

Ex #1


A car traveling with an initial velocity
of 6 m/s, accelerates at 2 m/s
2
, for 6
seconds. What is the car’s final
velocity?

Kinematic Equations
-

Ex #1
-

Ans


A car traveling with an initial velocity of 6
m/s, accelerates at 2 m/s
2
, for 6 seconds.
What is the car’s final velocity?

2
6 2 6 18
f i
f
V V at
m m m
V s
s s s
 
   
Sample Problems

2. You’re riding a unicorn at 25 m/s
and come to a uniform stop at a
red light 20 m away. What’s your
acceleration?

A:
-
15.6m/s
2


Practice Problems

3. With an average acceleration of
-
1.2
m/s
2
, how long will it take a cyclist to
bring a bicycle with an initial speed of
6.5 m/s to a complete stop?


A: 5.4 s


Practice Problems

4. Suppose a treadmill has an average
acceleration of 4.7
×

10
3

m/s
2
.

a.
How much does its speed change
after 5.0 min?

b.
If the treadmill’s initial speed is 1.7
m/s, what will its final speed be?


1.4
×

10
6

m/s and

3.1 m/s


Practice Problems

4. A dune buggy accelerates uniformly at

1.5 m/s
2

from rest to 22 m/s. Then
the brakes are applied and it stops
2.5 s later. Find the total distance
traveled.



A: 188.8m




If a baseball has zero velocity at some instant, is
the acceleration of the baseball necessarily zero
at that instant?


If a passenger train is traveling on a straight track
with a negative velocity and a positive
acceleration, is it speeding up or slowing down?


When you are out for a bike ride, you slow down
on your bike as you approach a group of hikers
on a trail. Explain how your acceleration can be
positive even though your speed is decreasing.


Small Group Questions