MOIZ DAWOODI
O’ LEVEL
O/A LEVEL PHYSICS
Momentum
1.6
ST U D E N T N A M E
PHYSICS WITH
0315 0805775
O'Levels
1.6 Momentum
1 An object of mass 50 kg accelerates from a velocity of 2.0 m / s to a velocity of 10 m / s in the same
direction.
What is the impulse provided to cause this acceleration?
A 250 N s B 400 N s C 850 N s D 2500 N s
2 A gas molecule strikes the wall of a container. The molecule rebounds with the same speed.
wall wall
gas molecule gas molecule
before hitting the wall after hitting the wall
What happens to the kinetic energy and what happens to the momentum of the molecule?
3 Which quantity is measured in newton seconds (N s)?
A impulse
B moment
C power
D work done
4
5
6
1 Fig. 1.1 shows a dummy of mass 70 kg used in a crash test to investigate the safety of a new car.
passenger dummy
barrier compartment
windscreen
Fig. 1.1
The car approaches a solid barrier at 20 m / s. It crashes into the barrier and stops suddenly.
(a) (i) Calculate the momentum of the dummy immediately before the crash.
momentum = ................................................................. [2]
(ii) Determine the impulse that must be applied to the dummy to bring it to rest.
impulse = ................................................................. [1]
(b) In the crash test, the passenger compartment comes to rest in 0.20 s.
Calculate the deceleration of the passenger compartment.
deceleration = ................................................................. [2]
(c) The seat belt and air bag bring the dummy to rest so that it does not hit the windscreen.
2
The dummy has an average deceleration of 80 m / s .
Calculate the average resultant force applied to the dummy, of mass 70 kg.
force = ................................................................. [2]
(d) The deceleration of the dummy is less than the deceleration of the passenger compartment.
Explain why this is of benefit for the safety of a passenger.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
........................................................................................................................................... [2]
2 Fig. 2.1 shows a hammer being used to drive a nail into a piece of wood.
hammer head
nail
wood
Fig. 2.1
The mass of the hammer head is 0.15 kg.
The speed of the hammer head when it hits the nail is 8.0 m / s.
The time for which the hammer head is in contact with the nail is 0.0015 s.
The hammer head stops after hitting the nail.
(a) Calculate the change in momentum of the hammer head.
change in momentum = ...........................................................[2]
(b) State the impulse given to the nail.
impulse = ...........................................................[1]
(c) Calculate the average force between the hammer and the nail.
average force = ...........................................................[2]
3 The engine of an unpowered toy train is rolling at a constant speed on a level track, as shown in
Fig. 3.1. The engine collides with a stationary toy truck, and joins with it.
moving
ving e
engine
statio
ationary
y tru
uck
k
track
tr k
Fig. 3.1
Before the collision, the toy engine is travelling at 0.32 m / s. The mass of the engine is 0.50 kg.
(a) Calculate the momentum of the toy engine before the collision.
momentum = [2]
(b) The mass of the truck is 0.30 kg.
Using the principle of conservation of momentum, calculate the speed of the joined engine
and truck immediately after the collision.
speed = [3]
Page 2 Mark Scheme Syllabus Paper
Question Answer Mark
1(a)(i) (momentum =) mv OR 70 × 20 C1
= 1400 kg m / s OR N s A1
a)(ii) same numerical answer as (a)(i) with either unit OR 1400 kg m / s B1
(b) (a = ) change of velocity / time OR (v – u) /t OR 20 / 0.2 C1
A1
100 m / s2
(c) (F =) ma OR 70 × 80 C1
5600 N A1
(d) Force / impact on passenger or dummy less (than without seat belt / airbag) M1
Passenger less likely to be injured / hurt / damaged A1
Page 2 Mark Scheme Syllabus Paper
2 (a mv – mu OR m(v – u) OR mv OR 0.15 × 8.0 C1
1.2 N s or kg m / s A
(b) 1.2 N s or kg m / s B
(c) F = (mv – mu) / t OR F = mv / t OR impulse / t OR 1.2 / 0.0015
.0
800 N A1
OR
(F =) ma OR m[(v – u) / t] OR 0.15 × 8 / 0.0015
.001
800 N (A1)
Page 2 Mark Scheme Syllabus Paper
3 (a p = mv in any form, words or symbols [1]
0.16 kg m / s OR N s [1]
(b) use of principle of conservation of momentum in words, symbols or numbers [1]
use of combined mass 0.5(0) + 0.3(0) OR 0.8(0) (kg) [1]
0.2(0) m / s [1]
