Name
Period
Impulse, Momentum, and Collisions
STUDY GUIDE- Write your answers on a SEPARATE sheet of paper.
Vocabulary – Define the following terms.
1. impulse
2. momentum
3. impulse-momentum theorem
4. closed system
5.
6.
7.
8.
isolated system
law of conservation of momentum
elastic collision
inelastic collision
Concept Questions – Answer the following questions.
1. The momentum of an object depends on what 2 quantities? mass and velocity
2. With what 2 equations could you use to calculate the impulse of an object? FΔt = mΔv
3. A
small
force over a small
time will produce a small change in momentum,
and a large
force over a large
time will produce a large change in momentum.
4. Why is it safer, in terms of impulse and momentum, to hit an airbag rather than your steering wheel
during an accident? impulse remains the same in both, but a smaller force is applied over a longer time
5. What types of materials experience nearly elastic collisions? steel marbles, trampolines, baseballs
6. What types of materials experience highly inelastic collisions? butter, clay, snowballs
7. In order to give a complete description of momentum, one must use the correct
units and
state a
direction
. For example, 5.5 kgm/s, left is a complete description of momentum.
8. Object A has 3 times as much mass as object B. If the two objects have the same velocity, compare the
momentum of object A to that of object B. object A has 3x the momentum
9. Momentum is a
vector
quantity because it has
direction
.
10. For momentum to be conserved in a collision, the system must be closed
and isolated , and
the momentum before the collision must equal
the momentum after the collision.
Problem Solving – Solve the following problems paying attention to units and significant figures.
1. Steven throws a 3.5 kg ball at a speed of 25 m/s. What is the momentum of the ball? 88 kg-m/s
2. What impulse is needed to slow a 45 kg object from 15 m/s to 12 m/s? -140 N-s
3. A force of 15 N acts on an object for 0.75 s. What is the impulse acting on the object? What is the
objects change in momentum? 11 N-s = 11 kg-m/s
4. A 550 kg car accelerates from 15 m/s to 25 m/s in 15 s by applying a constant force. How large of a
force is exerted? 370 N
5. A 78 kg defensive back moving 8.5 m/s tackles a 72 kg receiver moving at 7.5 m/s. What is the postcollision speed immediately after the tackle? 8.0 m/s
6. A 225 kg bumper car moving 2.5 m/s strikes a 198 kg car at rest. If the 225 kg comes to rest after they
collide, what is the speed of the 198 kg after the collision? 2.8 m/s
7. A 5.0 kg bowling ball moving at 2.3 m/s strikes a stationary 0.85 kg bowling pin. Immediately after the
head-on collision, the pin is moving 5.3 m/s. What is the post-collision velocity of the bowling ball?
1.4 m/s
kg
s
kg-m/s
m/s2
m
m/s
N
N
250 N = 300 N (with sig fig )
50 N
0.60 kg
153 kg = 150 kg (with sig fig )
7.5 m/s2
625 kg-m/s = 630 kg-m/s (with sig fig)
0 kg-m/s
100 m/s = 1.0 x 102 m/s (with sig fig)
Both have the same momentum of 820 kg-m/s.
42 kg-m/s