AP Physics 1 Impulse and Momentum Worksheet 3: Impulse and Change in Momentum Do your work on a separate sheet of paper. Draw diagrams for each problem and don’t forget about directions – momentum, velocity and impulse are VECTORS. 1. A bug and the windshield of a moving car collide. Indicate which of the following statements are TRUE. a. The impact force on the bug and the car are the same magnitude. b. The impulse on the bug and the car are the same magnitude. c. The change in momentum of the bug and the car are the same magnitude. d. The change in velocity of the bug and the car are the same. 2. A 1kg object, initially at rest, experiences the impulses represented in the graph at right. Describe the object’s motion after impulses A, B, and C. What is the velocity of the object after 12 sec? 6 8 10 12 2 4 3. Golf. Rocio strikes a 0.058 kg golf ball with a force of 272 N and gives it a velocity of 62.0 m/s, 30o above the horizontal. a) How long was Rocio’s club in contact with the ball? b) If the golf ball’s initial velocity of 62m/s is at an angle of 30o above the level ground, what is the momentum of the ball at its maximum height? c) What is the momentum of the ball right before it hits the ground? 4. Volleyball. A 0.24 kg volleyball approaches Tina with a velocity of 3.8 m/s. Tina bumps the ball, giving it a speed of 2.4 m/s in the opposite direction. What average force did she apply if the interaction time between her hands and the ball was 0.025 s? 5. Rockets. Small rockets are used to make tiny adjustments in the speeds of satellites. One such rocket has a thrust of 35 N. If it is fired to change the velocity of a 72,000 kg spacecraft by 63 cm/s, how long should it be fired? 6. A 95 kg fullback, running at 8.2 m/s, collides in midair with a 128 kg defensive tackle moving in the opposite direction. Both players end up with zero speed. a. Identify the “before” and “after” situations and draw a diagram of both. b. What is the fullback’s momentum before the collision? c. What was the change in the fullback’s momentum d. What was the change in the defensive tackle’s momentum? e. What was the defensive tackle’s original momentum? f. How fast was the defensive tackle moving originally? 7. A 12.0 g rubber bullet travels at a velocity of 150 m/s, hits a stationary 8.5 kg concrete block resting on a frictionless surface, and ricochets in the opposite direction with a velocity of -100 m/s. a. How fast will the concrete block be moving? b. Calculate and compare the K before and after the event. Use this comparison to determine the type of collision (elastic, inelastic, or explosion). 8. An object is moving so that its kinetic energy is 150 J and the magnitude of its momentum is 30.0 kg·m/s. Determine the mass and speed of the object. 9. A 730-N man stands in the middle of a frozen pond of radius 5.0 m. He is unable to get to the other side because of a lack of friction between his shoes and the ice. To overcome this difficulty, he throws his 1.2-kg physics textbook horizontally toward the north shore, at a speed of 5.0 m/s. How long does it take him to reach the south shore? 10. A 1345 kg car moving east at 15.7 m/s is struck by a 1923 kg car moving north. They are stuck together and move with an initial velocity of 14.5 m/s at = 63.50. Was the north moving car exceeding the 20.1 m/s speed limit? 11. A stationary billiard ball, with a mass of 0.17 kg, is struck by an identical ball moving at 4.0 m/s. After the collision, the second ball moves 600 to the left of its original direction. The stationary ball moves 300 to the right of the original ball’s original direction. What is the velocity of each ball after the collision? 12. A 4.00 kg model rocket is launched, expelling 50.0 g of burned fuel from its exhaust at a speed of 625 m/s. What is the velocity of the rocket after the fuel has burned? Hint: Ignore the external forces of gravity and air resistance. 13. a) A 0.030-kg bullet is fired vertically at 200 m/s into a 0.15-kg block that is initially at rest. How high does the combination rise after the collision, assuming the bullet embeds itself in the block? b) Another 0.030-kg bullet is fired horizontally at 200 m/s into a 0.15-kg block that is initially at rest. Again, the bullet embeds itself in the block after the collision. How far does the block/bullet slide if the coefficient of friction between the block and surface is 0.30? Answers 2. 0-2 sec: object at rest 2-4 sec: object accelerates at a rate of 2 m/s2 4-6 sec: object moving at constant velocity of 4 m/s2 6-8 sec: object decelerates at -2 m/s2 8-10 sec: object at rest 10-11 sec: object decelerates at -2 m/s2 11-12 sec: object moving at constant velocity of -2 m/s2 3. 0.013s 4. 59.5N 5. 1296s 6. b) 779N.s c) 779 N.s d) 779 N.s e) -779 N.s f) -6.1m/s 7. a) 0.35m/s b) Kbefore = 135 J, Kafter = 60.5 J so inelastic 8. m=3kg, v=10m/s 9. 61.7s 10. 21.9 m/s 11. v1’ = 2 m/s, v2’ = 3.46 m/s 12. 7.91m/s 13a) 56.6 m b) 189 m

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