I need 5-16

AP Physics 1 U7 - WS 2 - Momentum & Impulse page 1 Unit 7 - Momentum 3/24/15 Problems 1-4: There are two skateboards (A and B) next to each other on the floor. A kitty is standing on the left skateboard (A). Everything begins at rest. Each skateboard has a mass of 5 kg and the kitty has a mass of 1 kg. 1. The cat jumps onto the right skateboard with a velocity of 1 m/,. What velocity does skateboard A have as a result? 2. What will be the velocity of the cat and skateboard B after the cat lands on it? The cat then jumps back onto skateboard A with a speed of 3 m/s. What velocity will skateboard B have as a result? 4. After the cat lands on skateboard A, what velocity will they have? (Hint: there are two ways of solving this problem: either define your system to be A and C or define it to be A, C, and B. Make sure you use the right velocities in the system you choose.) 5. You kick a 2 kg soccer ball with a force of 15 N. If your foot is in contact with the ball for two tenths of a second, what speed will the soccer ball have after it's kicked? A pitcher throws a 0.4 kg baseball at 40 m/s. The batter hits the ball back at the pitcher with the same speed. a. If the ball is in contact with the bat for 0.1 s, what force did the bat exert on the ball? b. How does this force compare to the force the ball exerts on the bat? C. If the ball is hit back at the pitcher itcher at 30 m/s instead, how long was it in contact with the bat? d. What force would it take, assuming the contact time is 0.1 s, to make the ball travel 150 m? (Assume the ball is in the air for 6 seconds after being hit) 7. A 13 kg bomb explodes into three pieces. One piece, weighing 13.2 lbs flies off to the right with a speed of 20 m/s. A second piece that weighs 30 N flies off to the left with a speed of 30 m/s. What is the velocity of the third piece? 8. Discuss the following in terms of impulse and momentum: a. Why are padded dashboards safer in automobiles? b. Why are nylon ropes, which stretch considerably under stress, favored by mountain climbers? c. Why is it preferred that railroad cars be loosely coupled with slack between cars? If you throw a ball horizontally while standing on roller skates, you roll backwards. Will you roll backwards if you go through the motions of throwing the ball, but hold on to it instead? Explain your reasoning. 10. If a Mack truck and a Smart car traveling at equal speeds have a head-on collision, a. Which vehicle experiences the greater force of impact? b. Which vehicle experiences the greater change in momentum? c. Which vehicle experiences the greater acceleration? 11. While being thrown, a total force of 132 N acts on a baseball (mass = 140g) for a period of 4.5 x 10 2 sec. a. What is the magnitude of the change in momentum of the ball? b. If the initial speed of the baseball is 3 m/s, what is its speed immediately after leaving the pitcher's hand? C. When the batter hits the ball, a total force of 1320 N, opposite to the direction of the ball's initial motion, acts on the ball for 9.0 x 10" s during the hit. What is the final velocity of the ball? 12. A rocket, weighing 4.36 x 10# N, has an engine that provides an upward force of 8.9 x 105 N. It reaches a maximum speed of 860 m/s. For what period of time, after launch, must the engine burn in order to reach this speed? 13. A tennis player returns a 30.0 m/s serve straight back at 25.0 m/s, after making contact with the ball for 0.50 s. If the ball has a mass of 0.20 kg, what is the force she exerted on the ball? 14. A 50.0 kg cart is moving across a frictionless floor at 2.0 m/s. A 70.0 kg boy, riding in the cart, jumps off so that he hits the floor with zero velocity. a. What impulse did the boy give to the cart? b. What was the velocity of the cart after the boy jumped? 15. Two girls with masses of 50.0 kg and 70.0 kg are at rest on frictionless in-line skates. The larger girl pushes the smaller girl so that the latter rolls away at a speed of 10.0 m/s. a. What is the effect of the action on the larger girl? b. What is the impulse that each girl exerts on the other? 16. A billiard ball will stop short when it collides head-on with another ball that is at rest. The ball cannot stop short, however, if the collision is not exactly head-on but is at an angle. Explain why this is so in terms of momentum