# PHYSICS

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What magnitude of force, acting for 0.025 s, will change the velocity of a 100 g ball from 30 m/s eastward to 40 m/s westward?

A girl holds a 1.7 kg air rifle loosely and fires a bullet of mass 2 g. The muzzle velocity of the bullet is 160 m/s. What is the magnitude of the recoil velocity of the gun?

An astronaut of mass 70 kg carries an empty oxygen tank of mass 14 kg. He throws the tank away from himself with a speed of 3 m/s. With what velocity does the astronaut start to move through space?

Two carts are stationary with a compressed spring between them. When the spring is released, the two carts move apart. After the spring is released, one cart m = 3 kg has a velocity of 0.74 kg m/s east. What is the magnitude of the velocity of the second cart (m = 1.7kg) after the spring is released?

In a freight yard a train is being made up. An empty freight car, coasting at 9 m/s, strikes a loaded car that is stationary, and the cars couple together. Each of the cars has a mass of 3200 kg when empty, and the loaded car contains 13000 kg of bottled soft drinks. With what speed does the combined mass start to move?

A cart with a mass of 0.6 kg moving at 4 m/s collides with a stationary cart that has a mass of 0.6 kg. If the two carts stick together after the collision, what is the final velocity?

A rock (m = 1.5 kg) moving at 4.2 m/s north collides with a ball (m = 0.061 kg) that is initially at rest. What is the velocity of the rock after the collision if the velocity of the ball after the collision was 8.4 m/s north?

A 45 kg cart is moving across a frictionless floor at 1.7 m/s. A 60 kg boy, riding in the cart, jumps off the cart so that he hits the floor moving forwards in the initial direction of the cart's motion with a velocity of 2.8 m/s. What is the velocity of the cart after the boy jumped?

• PHYSICS -

change in velocity = 70

force * time = change in momentum (or impulse)

F * .025 = 0.100 * 70

The next one is conservation of momentum. I am not going to do them all for you. You try.