Collisions

1) Car #1 has a mass of 850 kg, and is sitting at rest at a stop sign. Car #2 has a mass of 1100 kg and is moving at 12 m/s. The driver of car #2 isn’t paying much attention and drives into the back of

car #1. After the collision, car #2 is moving at 4.0 m/s. How fast is car #1 moving?

After you find the velocity of car #1, add the final velocities together and compare them with the sum of the initial velocities. Are they the same?

2) A car moving at 25 m/s has a mass of 1700 kg. A second car, moving at – 15 m/s, has a mass of 1200 kg. They collide. After the collision, the 1700 kg car is moving at 9.5 m/s. What is the velocity of the other car?

3) If a car has a mass of 1450 kg, and a speed of 30 m/s, how much impulse is required to stop it?

4) If the car in Question 3 were to drive into a large tree, stopping in 0.35 s, how much force would the tree exert on the car? Also, would the car exert more force on the tree, or would the tree exert more force on the car?

5) Two football players are running toward each other. The first guy has a mass of 75 kg and a speed of 3.0 m/s. The second guy has a mass of 90 kg and a speed of 5.0 m/s. As they collide, one player grabs onto the other – it’s an inelastic collision. How fast do the two of them move after the collision?

6) A ball falls at 5.5 m/s. It has a mass of 0.75 kg. After it hits the ground, it bounces upward at 3.9 m/s. How much impulse was required to make the ball bounce?