Name: ______________________________________
Date: __________________
AP Physics 1
Unit 2 Homework
1.
Per. _________
A car is driven 80 km west in 1 hour and then 70 km east in 2 hour. East is the positive direction.
a) What is the average velocity and average speed of the car in km/hr ?
b) If the car drives 80 km west at 100 km/hr and then drives 70 km east at 31.8 km/h, what is the
average velocity of the car for the entire trip?
12
2. Examine the position-time
graph at right
10
C
8
x (m)
6
D
B
A
E
4
F
2
5
10
15 20 25
Time (s)
a. How far does the object travel between 0 and 30 s?
b. How far does it travel between 30 s and 35 s
c.
What is the displacement of the object between 30 s and 35 s
d.
At which points is the velocity positive?
e.
At which points is the velocity negative?
f.
At which points is the velocity about zero?
g.
What is the average velocity of the object for the first 30 s
h.
What is the average speed of the object for the first 30 s
i.
At which points is the acceleration positive?
j.
At which points is the acceleration negative?
k.
At which points is the acceleration about zero?
30
35
40
3. A walker and a runner leave your front door at the same time. They move in the same direction at
constant velocities. Describe the position-time graphs of each.
4. The following graphs represent the motions of two different bicyclists. With which of the statements
about the motions do you agree or disagree? Explain your choice.
5.
Bike B
x (m)
v (m/s)
Bike A
t (s)
t (s)
a) Bike A started moving at constant positive velocity.
b) Bike B climbed over a flat hill.
c) Bike A stopped twice during the trip.
d) Bike B stopped twice during the trip.
e) The last part of the trip bike A was not moving
f) The last part of the trip bike B was moving at constant speed in the negative direction.
g) The last part of the trip bike A was moving at constant speed in the negative direction.
h) When we started observing Bike B it was moving at constant positive velocity.
i)
When we started observing bike A it was moving at increasing velocity in the positive direction,
then it reached some constant velocity (positive) and continued moving for a while, then its velocity
started decreasing and it some point it became zero. Then it continued to increased in the negative
direction until it reached some new velocity which it maintained for a while.
j) When we started observing bike B it was moving at constant velocity in the positive direction, then
it stopped for a while, then it started going back to the origin and then in the negative direction.
Finally it stopped
Blue Car: Position vs. Time
5.
Red Car: Velocity vs. Time
8
8
6
6
4
2
0
-2
0
2
4
6
8
10
12
14
16
Velocity (m/s)
Position (m)
4
2
0
-2
-4
-4
-6
-6
-8
0
2
4
6
8
10
12
14
-8
Time (s)
Time (s)
The two graphs above may look similar, but they actually represent two very different motion patterns.
Calculate the answers to the following for both the Red car and the Blue car:
BLUE CAR
velocity at t = 3 seconds
average velocity from
t = 0 s to t = 2 s
velocity at t = 5 seconds
average velocity from
t = 6 s to t = 10 s
maximum speed for the
whole trip
In which interval(s) was
the car’s velocity negative
displacement during the
first 2 seconds
displacement during the
first 4 seconds
During which time
interval(s) was the car’s
velocity zero
During which intervals
was the car’s acceleration
zero
At what time(s) did the car
change direction?
RED CAR
16
v (m/s)
5. Refer to the following v-t graph of an object’s motion.
16
14
12
10
8
6
4
2
0
-2 0
-4
-6
-8
-10
-12
-14
-16
-18
2
4
6
8
10
12
14
16t
(s)
Shade or check the time intervals that apply for the v-t graph given above
0-3s
3-5s
5-6s
6-8s
Moving in + direction
Moving in - direction
At rest
Speeding Up
Slowing Down
Constant speed
Greatest distance
Least distance
Negative acceleration
Positive acceleration
Greatest acceleration
(magnitude)
When does the object change direction?
What is the acceleration at 1 s? at 4 s? at 7 s? at 14 s?
What is the average velocity for the first 3 sec?
8-9s
9-13s
13-15s
none
0
16
14
12
10
8
6
4
2
0
-2 0
-4
-6
-8
-10
-12
-14
-16
-18
2
4
6
8
10
12
14
16
t (s)
2
4
6
8
10
12
14
16t
(s)
0
2
4
6
8
10
12
14
16
t (s)
a (m2/s)
v (m/s)
x (m)
Using the same v-t graph, plot the corresponding position-time and acceleration-time
graphs (place the horizontal axis appropriately, scale appropriately). Check your answers
above (in the table and questions) with the x-t and a-t graphs.
What is the average velocity for the first 8 sec?
What is the average velocity between 4 and 10s?
What is the average speed for the first 8 sec?