Drayton Manor High School
Momentum Test
Name:______________________
Q1. Which one of the following has the same unit as the rate of change of momentum?
A
work
B
energy
C
acceleration
D
weight
(Total 1 mark)
Q2. The nucleus of a radioactive isotope X is at rest and decays by emitting an α particle so that a
new nuclide Y is formed. Which one of the following statements about the decay is correct?
A
The momentum of Y is equal and opposite to the momentum of the α particle.
B
The momentum of Y is equal to the momentum of X.
C
The kinetic energy of Y is equal to the kinetic energy of the α particle.
D
The total kinetic energy is the same before and after the decay.
(Total 1 mark)
Q3. Trolley T1, of mass 2.0 kg, collides on a horizontal surface with trolley T2, which is also of
mass 2.0 kg. The collision is elastic. Before the collision T1 was moving at 4.0 m s–1 and
T2 was at rest.
Which one of the following statements is correct?
Immediately after the collision
A
T1 is at rest and T2 moves at 4.0 m s–1.
B
T1 will rebound from T2 at 4.0 m s–1.
C
T1 and T2 will both move at 2.8 m s–1.
D
T1 and T2 will both move at 1.4 m s–1.
(Total 1 mark)
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Drayton Manor High School
Q4. A stationary unstable nucleus of mass M emits an α particle of mass m with kinetic energy
E.
What is the speed of recoil of the daughter nucleus?
A
B
C
D
(Total 1 mark)
Q5. A golf club strikes a stationary golf ball of mass 4.8 × 10–2 kg and the ball leaves the club
with a speed of 95 m s–1. If the average force exerted on the ball is 7800 N, how long are
the ball and club in contact?
A
5.8 × 10–4 s
B
1.2 × 10–2 s
C
0.51 s
D
0.58 s
(Total 1 mark)
Q6. A cricket ball is travelling at a speed of 32.5 ms–1 when it is hit by a bat. After impact, the
ball has the same speed but is travelling in the opposite direction. The mass of the ball is
0.156 kg.
(a)
Calculate the change in momentum of the cricket ball. State an appropriate unit for
your answer.
......................................................................................................................
......................................................................................................................
change in momentum ................................................
unit ................................................
(3)
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(b)
The bat is in contact with the ball for 3.80 ms.
Calculate the force exerted by the bat on the ball.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
force ..............................................N
(2)
(Total 5 marks)
Q7. The graph shows how the momentum of two colliding railway trucks varies with time.
Truck A has a mass of 2.0 × 104 kg and truck B has a mass of 3.0 × 104 kg. The trucks are
travelling in the same direction.
(a)
Calculate the change in momentum of
(i)
truck A,
.............................................................................................................
(ii)
truck B.
.............................................................................................................
(4)
(b)
Complete the following table.
Initial
velocity/m s–1
Final
velocity/m s–1
Initial kinetic
energy/J
Final kinetic
energy/J
truck A
truck B
(4)
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(c)
State and explain whether the collision of the two trucks is an example of an elastic collision.
......................................................................................................................
......................................................................................................................
......................................................................................................................
......................................................................................................................
(3)
(Total 11 marks)
Q8. A 0.30 g fly moving at 1.5 m/s is trapped by a spider’s web. The fly comes to rest in a time
of 0.40 s. Calculate the magnitude of:
(a) the change in momentum of the fly;
......................................................................................................................
......................................................................................................................
(2)
(b) the average force exerted by the web on the fly.
......................................................................................................................
......................................................................................................................
(3)
Q9. A bullet of mass 30 g is fired at a speed of 140 m/s into a stationary block of wood of mass 460g.
The bullet becomes embedded inside the wood.
(a) Calculate the common speed of the block of wood and the bullet after the impact. (2)
(b) Calculate the initial kinetic energy of the bullet and the final kinetic energy of the block of
wood and the embedded bullet. (2)
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(c) Use your answers to b to suggest whether the collision between the bullet and the block of
wood is inelastic or elastic. (1)
Q10. A 850 kg cannon fires a 20 kg shell at a velocity of 180 m/s
(a) Calculate the final momentum of the shell. (2)
(b) What is the magnitude of the momentum of the cannon immediately after the shell is fired?
(You may assume that the cannon is initially at rest.) (1)
(c) Calculate the recoil velocity V of the cannon. (2)
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M1. D
[1]
M2. A
[1]
M3. A
[1]
M4. A
[1]
M5. A
[1]
(a)
M6.
32.5 × 0.156 or 65 × 0.156: any mass × velocity
10.07/10.1/10 ignore sf
kg ms–1 (accept Ns)
3
(b)
their a/3.80 (× 10–3) ignore power of 10 error
2670 (N) ecf
2
[5]
(a)
M7.
(i)
(change in momentum of A) = – (1) 25 × 103 (1)
kg m s–1 (or N s) (1)
(ii)
(change in momentum of B) = 25 × 103 kg m s–1 (1)
4
(b)
initial vel/m s–1
final vel/m s–1
initial k.e./J
final k.e./J
truck A
2.5
1.25
62500
15600
truck B
0.67
1.5
6730
33750
(1)
(1)
(1)
(1)
4
(c)
not elastic (1)
because kinetic energy not conserved (1)
kinetic energy is greater before the collision (or less after) (1)
[or justified by correct calculation]
[11]
M8. a) ∆
∆ = (0.3/1000)(-1.5) = 4.5x10-4kgm/s
b) Ft = ∆
F = ∆ / = (4.5x10-4kgm/s)/(0.40s) = 1.13x10-3N
M9. a) total initial momentum = total final momentum
v = 8.6m/s
b) initial kinetic energy of bullet = 294J
final kinetic energy of bullet and block = 18J
c) kinetic energy not conserved, therefore inelastic
M10. A) 3600 kgm/s
b) -3600 kgm/s
c) 4.2m/s
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