12.1 Momentum and impulse
Check your learning 12.1
Describe and explain
1
Describe what momentum is.
2
Explain what is meant by a change in momentum.
3
Explain what a force–time graph measures.
4
Describe impulse.
5
Calculate the magnitude of the momentum of the following moving objects:
a
a 1000 g bowling ball moving at 1.6 m s–1
b
a 2.0 tonne car moving at 15 m s–1
c
Earth in its journey around the Sun. (Earth’s mass is 6 × 1024 kg and its average radius of orbit is 1.5 × 1011
m)
6
A 900 kg car is travelling east at a velocity of 40 km h−1 when it is approached by a 290 kg motorbike travelling
west at a velocity of 90 km h−1. Calculate the total momentum of the system.
7
A proton of mass 1.67 × 10–27 kg is accelerated from 2 × 104 m s–1 to 9 × 105 m s–1. Calculate the change in
momentum.
Apply, analyse and interpret
8
A force of 3 millinewton acts on an electron for 0.15 seconds. Determine the impulse imparted on the electron.
9
A mass of 2.4 kg is moving at 6.0 m s–1 north.
a
Determine how long, and in what direction, a frictional force of 5.6 N must act to bring it to rest.
b
10
Calculate the impulse acting on the object.
A tennis ball is struck by a racquet as shown by the graph (Figure 4).
FIGURE 4 Force-time graph
Determine the:
11
a
impulse given to the ball
b
change in momentum of the ball.
Consider Figure 5 which shows a force–time graph for an object over 10 s.
FIGURE 5 Force-time graph
a
Calculate the impulse imparted to the object over the whole 10 seconds.
b
Determine the greatest impulse given.