Physics 432 Momentum Impulse & Momentum Problems 1. In a typical collision between a baseball and bat, the ball (mass = 0.15 kg) has an initial velocity of 40 m/s in the +x direction and a final velocity of 45 m/s in the –x direction. a) Calculate the impulse that the bat exerts on the ball during the collision. b) Suppose that the total time of the collision is 0.6 s. Calculate the average force exerted on the ball by the bat during that time. c) Suppose that the velocity of the bat (mass = 0.90 kg) just before the ball hits the bat is 30 m/s in the opposite direction to the ball. Calculate the magnitude and direction of the velocity of the bat just after the ball rebounds off the bat. 2. Block 1 of mass of 10 kg initially has a speed of 15 m/s. It collides with block 2 of mass 15 kg, which is initially stationary. After the blocks collide, they stick and move together along a frictionless surface. a) What is the momentum of Block 1 before the collision? b) What is the momentum of Block 2 before the collision? c) What is the momentum of the blocks combined after the collision? d) What is the velocity of the blocks after the collision? 3. Boxcar 1 of mass 5000 kg is moving down the railroad track with a speed of 8 m/s. It collides and couples to boxcar 2, which is initially at rest. Together, they move down the track with a velocity of 4.8 m/s. a) What is the momentum of boxcar 1 before the collision? b) What is the mass of box car 2? 4. A Purdue football player of mass 74 kg runs at a speed of 13 m/s toward our Illini defensive line. They collide head on and the running player is totally stopped. a) With their helmets on, the players collide with each other for 0.39 s. Find the average force exerted on the player’s head. b) Suppose they were playing 100 years ago without helmets. Their heads would have collided for 0.019 s. Find the average force for this time. 5. A boxcar of mass 1000 kg traveling at 5 m/s strikes another car initially at rest and then they stick together. After the collision, the two cars move at a speed of 2 m/s. What was the mass of the second car? 6. A rifle of mass 2.5 kg fires a bullet with a mass of 50 g at a velocity of 200 m/s. What is the recoil velocity of the rifle? 7. Two men push a stalled 800 kg car with a combined force of 630 N and achieve a final speed of 3 m/s. How long did the men push the car?