Quiz on Momentum/question paper : P.1 F.4 Physics Quiz on Momentum
Time Allowed : 35 min. Class : 4 ____ Name : ______( ) Total Marks : 30 marks
v p Equation Given: Force F = m = t t 2 Kinetic energy EK = ½mv
Gravitational potential energy EP = mgh For uniformly accelerated motion : v = u + at s = ut + ½at2 2 2 v = u + 2as Take gravitational acceleration g = 10 ms-2 Section A: M.C. (Total 15 marks, 1.5 marks each) Write down the choice in the spaces provided on the answer sheet.
1. At the moment the baseball player catches the ball, he moves his hands towards himself. This can reduce
A. the impulse of the ball. B. the time to stop the ball. C. the force required to stop the ball. D. the work done to stop the ball.
2. A bowling ball is travelling at a speed of 5 m s−1 towards a pin as shown. 5 m s1
After collision, the speed of the ball reduces to 4 m s−1. Suppose the ball has six times the mass of the pin. Find the speed of the pin just after it bounces off from the ball.
A. 4 m s−1 B. 5 m s−1 C. 6 m s−1 D. 7 m s−1
1 1 3. In a linear air track experiment, two riders A and vA = 4 m s vB = 5 m s B of the same mass move towards each other at 4 m s−1 and −5 m s−1 respectively as shown.
Assuming that the collision is elastic, what are rider A rider B the velocities of riders A and B after collision?
rider A rider B A. 0 1 m s−1 B. −1 m s−1 0 C. −4 m s−1 5 m s−1 D. −5 m s−1 4 m s−1
4. A skateboard of mass 1.8 kg is travelling at a horizontal speed of 5 m s−1. A boy of mass 30 kg then jumps onto it vertically. Find their common horizontal speed.
A. 0.157 m s−1 B. 0.283 m s−1 C. 0.3 m s−1 D. 5 m s−1 Quiz on Momentum/question paper : P.2 5. The graph below shows how the momentum momentum / kg m s1 of an object changes with time.
B In which time interval is the unbalanced 15 force acting on the object the greatest? D E 10 A. AB 5 B. BC C C. CD D. DE 0 time / s A 1 2 3 4
6. A bus of mass 6000 kg travelling at a speed of 18 m s-1 collides with a lorry of mass 12 000 kg which is initially at rest. The collapsed vehicles moves together and eventually stops. Suppose the average retarding force on the collapsed vehicles is 20 000 N. Find the time taken for the collapsed vehicles to come to rest.
A. 2.7 s B. 5.4 s C. 8.1 s D. 16.2 s
7. A fire hose ejects water at a constant rate towards a wall. The water splashed back by the wall is negligible. In which of the following situation will the water exert a greater force on the wall? (1) The hose ejects water at a higher rate. (2) The collision between the water the wall lasts longer. (3) The density of the water increases. A. (1) only B. (3) only C. (1) and (2) only D. (1) and (3) only
8. A 2 kg wooden box moving on a smooth table with speed of 2 ms-1 is hit perpendicularly by a 3.85 g wooden box bullet moving at 900 m s−1 as shown. The bullet θ embeds into the box and they move together at an angle θ from the initial direction of motion of the ball. Find θ.
A. 0° B. 30° C. 60° D. 90° bullet
9. Two trolleys A and B are placed side by side on a button horizontal track as shown. When the button on trolley A is pressed, the retractable plunger of trolley trolley A trolley B A springs out. As a result, the trolleys move in opposite directions.
Suppose the mass of trolley A is greater than that of trolley B. Soon after the trolleys depart,
(1) the speed of trolley A is lower than that of trolley B. (2) the magnitude of momentum of trolley A is smaller than that of trolley B. (3) the kinetic energy of trolley A is less than that of trolley B.
A. (1) and (2) only B. (1) and (3) only C. (2) and (3) only D. (1), (2) and (3) Quiz on Momentum/question paper : P.3 10. A trolley travels with constant velocity to the right on horizontal ground and collides with a light helical spring attached to a wall fixed to the ground (earth) as shown. At the instant that the trolley comes momentarily to rest during collision, what has happened to the initial momentum of the trolley?
A. It has been transferred to the earth. B. It has been stored in the spring. C. It has been destroyed by the friction due to the ground. D. It has been lost because the collision was not perfectly elastic.
Section B: Structural Questions (Total 15 marks)
1. lorry car
A car of mass 1000 kg moves along a straight road with a speed 10 m s–1. It collides with a lorry of mass 3000 kg, which is initially at rest. Immediately after the collision, the lorry moves forward with a speed 4.5 m s–1. The time of contact of the car and the lorry is 0.5 s. (a) Calculate the speed of the car immediately after the collision. (2 marks) (b) (i) Calculate the average force acting on the lorry during the collision. (2 marks) (ii) Is the magnitude of the average force acting on the car during the collision greater, smaller or equal to the average force acting on the lorry? Explain briefly. (2 marks) (c) Calculate the change in kinetic energy for the collision of the car and lorry. Account for the change, if any. (3 marks)
2. A tennis ball travelling at a speed of 10 m s 1 is hit back by a racket as shown. It is known that the mass of the tennis ball is 57 g. The variation of the force acting on the tennis ball with time during the impact is as shown.
(a) At what time does the tennis ball have the greatest acceleration? (2 marks) force / N (b) (i) Find the area under the above graph. (1 mark) 200
(ii) What physical quantity does this area represent? (1 mark)
(c) Find the speed of the tennis ball just after the 100 impact. (2 marks)
End of Question Paper 0 5 10 time / ms Quiz on Momentum/answer sheet : P.4 Answer Sheet for F.4 Quiz on Momentum Class: 4 ____ Name:______( ) Section A: Multiple Choices (Total 15 marks, 1.5 marks each) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Section B: Structural Questions: (Total 15 marks)
1. (a)
(2 marks)
(b) (i)
(2 marks) (ii)
(2 marks) (c)
(3 marks) 2. (a)
(2 marks) (b) (i)
(1 mark)
(ii) (1 mark) (c)
(2 marks) End of Answer Sheet