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REVISION : FORCE , IMPULSE AND MOMENTUM – WORKSHEET 1
1. 1. Rank the objects (A – E) in order of increasing momentum.
mA  30 g
mE  20 g
mD  10 g
vB  5 m / s
vA  3 m / s
Least
mC  300 g
mB  40 g
1________
5________
vC  2 m / s
vD  5 m / s
2________
3________
vE  7 m / s
4________
Greatest
2. 2. The Position vs. Time graph is shown for an object of mass 0.60 kg.
Draw the corresponding Momentum vs. Time graph. (Use an appropriate
numerical scale for your Momentum vs. Time graph).
p (kg  m / s )
x ( m)
20
15
10
t ( s)
5
2
2
4
6
8
4
6
8
t ( s)
3. 3. The Momentum vs. Time graph is shown for an object of mass 500 g.
Draw the corresponding Acceleration vs. Time graph. (Use an appropriate
numerical scale for your Acceleration vs. Time graph).
p ( kg  m / s )
a(m / s 2 )
20
15
10
t ( s)
5
2
2
4
6
8
t ( s)
4
6
8
2
4. Explain how the crumple zones of a car can reduce the injury to the
passengers of a car. You should refer to the relationship between force and
momentum in your answer.
5. In a car the driver’s head is moving horizontally at 8.0 m s-1 and collides
with an air bag as illustrated in Figure 1. The time taken for the driver’s head
to come to a complete stop is 1.6 x10-1 s. This collision may be modelled as a
simple horizontal collision between the head of mass 7.0 kg and the air bag.
5.1 Calculate the magnitude of the average contact force that the air bag exerts
on the driver’s head during this collision.
5.2 Explain why the driver is less likely to suffer head injury in a collision with
the air bag than if his head collided with the car dashboard, or other hard
surface.
6. A truck of mass 2000kg collides with another stationary truck of mass
3000kg. If after the collision both trucks move of together with a speed of
5m/s what was the initial speed of the first truck?
6.1 What is meant by an elastic collision?
6.2 Show that the collision in the Q6.1 above is ineleastic.
7. A 4 kg object is moving 15 m/s to the right. A 6 N force pushes for 5 seconds to
the left.
A. How much momentum does it start with?
B. How much impulse acted on the object?
C. What is it’s change of momentum?
D. Calculate the final velocity of the object.
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8. A 10 kg object is 5 m/s moving to the left while a 3 kg object is going 4 m/s
to the right. (Remember your sign convention)
A) Find the momentum of the 10 kg object .
B) Find the momentum of the 3 kg object.
C) Find the net momentum of both objects.
9. A 2kg object at moving 4m/s. A 6N force pushes for 5 sec.
Calculate the final speed of the object.
10. Slim Jim pushes on an object that was already moving as shown in the
sketch below.
A. Under the diagram, calculate the momentum before and after and the
impulse Jim gave to the box.
B. What does the impulse equal?
11.
The diagram above shows two objects before and after they collide.
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A. On the diagram above calculate and label the net momentum before and after.
B. How does the net momentum before compare with the net momentum after?
12. Slim Jim is running 2 m/s towards a box that is at rest. Jim then jumps onto
the box and the two slide together.
A. On the diagram, calculate the net momentum before.
B. What is the total mass of Jim and the box afterwards?
C. Since momentum is always conserved, how much net momentum is there
afterwards?
D. Under the diagram, calculate the final velocity of Jim and the box.
13. A 3 kg cannonball is shot from a 200 kg cannon. The cannon recoils
backwards at 0.4 m/s backwards. What is the velocity of the ball after it is
shot?
A. Since the ball is sitting in the cannon, beforehand, what is the initial velocity
of the cannon and ball?
B. What is the net momentum before?
C. Since momentum MUST be conserved, how much total momentum must
there be afterwards?
E. Is the final velocity of the cannon + or −?
F. Following the same procedure as the previous problem, solve for the final
velocity of the ball.
EDUCATOR : h. s. hamid
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