Self-Test: Momentum in 1D and 2D Test #2
Suggested Time: 60 minutes

 1 A large mass, M, collides with a stationary small mass, m. During the collision, the forces exerted on each mass are measured. Which of the following is correct about the magnitude of the forces? A. No force is exerted during the collision. B. The large mass, M, exerts a greater force on the small mass, m. C. The small mass, m, exerts a greater force on the large mass, M. D. Both masses exert equal forces on each other during the collision. 2 A 0.40 kg ball rolls at 8.5 m/s towards a player. The player kicks the ball so that it then travels at 15.2 m/s in the opposite direction. What is the magnitude of the impulse that the ball sustained? A. 1.3 N.s B. 2.7 N.s C. 4.7 N.s D. 9.5 N.s 3 Identify momentum and kinetic energy as scalar or vector quantities. 4 A 1.0 kg cart moves to the right at 6.0 m/s and strikes a stationary 2.0 kg cart. After the head-on collision, the 1.0 kg cart moves back to the left at 2.0 m/s and the 2.0 kg cart moves to the right at 4.0 m/s. In this collision A. only momentum is conserved. B. only kinetic energy is conserved. C. both momentum and kinetic energy are conserved. D. neither momentum nor kinetic energy is conserved. 5 The graph below shows momentum, p, versus time, t, for a spacecraft while it is firing its rocket engines in space. What does the slope of this graph represent? A. the mass of the spacecraft B. the velocity of the spacecraft C. the net force on the spacecraft D. the work done on the spacecraft 6 Two cars collide head-on and come to a complete stop immediately after the collision. Which of the following is correct? 7 Which of the following is equal to impulse? A. Energy B. Momentum C. Change in energy D. Change in momentum 8 A 1.50 ´103 kg car travelling at 11.0 m/s collides with a wall as shown. The car rebounds off the wall with a speed of 1.3 m/s. If the collision lasts for 1.7 s, what force does the wall apply to the car during the collision? A. 8.6 ´103 N B. 1.1 ´104 N C. 1.5 ´104 N D. 1.8 ´104 N 9 A 1 500 kg car travelling at 25 m/s collides with a 2 500 kg van stopped at a traffic light. As a result of the collision the two vehicles become entangled. With what initial speed will the entangled mass move off, and is the collision elastic or inelastic? 10 Three objects travel as shown. What is the magnitude of the momentum of object R so that the combined masses remain stationary after they collide? A. 19 kg × m/s B. 30 kg × m/s C. 36 kg × m/s D. 48 kg × m/s 11 A stationary object explodes into two fragments. A 4.0 kg fragment moves westwards at 3.0 m/s. What are the speed and kinetic energy of the remaining 2.0 kg fragment? 12 A 1 000 kg vehicle travelling westward at 15 m/s is subjected to a 1. 0 ´104 N×s impulse northward. What is the magnitude of the final momentum of the vehicle? A. 5.0 ´103 kg × m/s B. 1.5 ´104 kg × m/s C. 1.8 ´104 kg × m/s D. 2.5 ´104 kg × m/s 13 Consider the collision between the vehicles in the photograph below. The collision is inelastic. Define inelastic. Give at least two pieces of evidence that show this to be an inelastic collision. (4 marks) 14 Two steel pucks are moving as shown in the diagram. They collide inelastically. Determine the speed and direction (angle q) of the 1.3 kg puck before the collision. (7 marks) 15 A space vehicle made up of two parts is travelling at 230 m s as shown. An explosion causes the 450 kg part to separate and travel with a final velocity of 280 m/s as shown. a) What was the momentum of the space vehicle before the explosion? (2 marks)   b) What was the magnitude of the impulse on the 1 200 kg part during the separation? (3 marks) c) Using principles of physics, explain what changes occur, if any, to the i) momentum of the system as a result of the explosion. (2 marks) ii) kinetic energy of the system as a result of the explosion. (2 marks) 16 During a motor vehicle accident an unbelted passenger experienced a force which varied with time as shown on the graph. a) Calculate the area of the shaded region in the graph. (1 mark) b) What does this area represent? (2 marks) c) If the passenger was wearing a seatbelt properly, the maximum force would have been one third the force experienced without the seatbelt. Sketch on the graph below how the force on the belted passenger might have varied with time. (2 marks) 17 A 360 kg roller coaster car travelling at 18 m/s collides inelastically with a stationary 240 kg car on a section of horizontal track as shown in the diagram below. To what maximum height, h, do the combined cars travel before rolling back down the hill? (Assume no friction.) (7 marks) 18 Sally is driving south in her 2500 kg pickup truck at 3.8 m/s when she collides with Willy driving west in his 1200 kg car at 4.5 m/s. The two vehicles lock together and slide over the wet parking lot. Find the speed and direction of the damaged vehicles immediately after the collision. (7 marks) 19 A rocket motor, capable of generating a 24 N.s impulse, is attached to a stationary frictionless 3.0 kg cart. The rocket motor is ignited.   a) What will the velocity of the cart be immediately after the rocket motor burns out? (3 marks) b) What is the resulting kinetic energy of the cart? (2 marks) c) A frictionless cart of larger mass will end up with less kinetic energy when powered by an identical rocket motor. Using principles of physics, explain this result. (4 marks)

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