Learning Tweet
 Units of momentum (change in momentum) = kgm/s
 Change in momentum depends on the size of the force
and the time it acts
 Change in momentum = resultant force (N) x time (s)
Unscramble the words & make two
sentences
NCEDSTI
EMIT
ELVICYT
HAGPR
EPEDS
CELECATNIOAR
DISTANCE
TIME
VELOCITY
GRAPH
SPEED
ACCELERATION
Momentum answers 1
A–
B
C
football = 12.5 kg m/s
Tennis ball leaving racquet = 3kg m/s
Golf ball = 2.05 kg m/s
Car = 22000 kg m/s
Lorry = 130 000 kg m/s
Van = 77500 kg m/s
sprinter = 500 kg m/s
Dog = 120 kg m/s
Cyclist = 910 kg m/s
Momentum answers 2
1
a
b
c
d
2
5000 kg m/s
31 600 kg m/s
720 000 kg m/s
480 000kg m/s
1.8 x1029 kg m/s
3
31.6 m/s (about 70 mph )
Momentum answers 3
1
A
B
2
A
B
C
23000 kg m/s
- 5400 kg m/s
9 kg m/s
-9kg m/s
18 kg m/s
Change in momentum
 Momentum = Mass x velocity
 Force x time (during which the force acts) = change in
momentum
Problems
 A snooker cue hits a ball.
 The ball has a mass of 0.17 kg and starts moving with a velocity of
1.4m/s.
 A What is the momentum of the ball
 Momentum = 0.17 x 1.4 = 0.238 kg m/s
 B The contact between the cue and the ball lasts for 0.1s. What is the
average force exerted on the cue ball during this time?
 F x t = change in momentum
 F= change in mom/time = 0.238/0.1 = 2.38 N
Problems (2)
 A motorcycle with a mass 200kg has a rider with a
mass 50kg. It is travelling at 27 m/s (60 mph)
 a What is the momentum of motorcycle & rider
 b What braking force is needed to bring the
motorcycle and rider to stop in 5s?
Problems (3)
 A car (mass 1025kg) has collided with a brick wall. It
was travelling at 23m/s(50mph)
 What was the momentum of the car
 The accident investigator estimated that it took 1.8s to
stop. What average force was exerted on the car during
the collision.