when

8.) In this photo, a fire extinguisher provides the impulse for a hallway rocket cart. Which is NOT true about the motion of the rocket cart and person? a.) The cart and person are propelled as a result of gas from the fire extinguisher pushing against air in the room. b.) The force of the gas on the cart and person is equal and opposite to the force of the person and cart on the expelled gas.      c.) The momentum of the cart and person is equal in magnitude and opposite in direction to the momentum of the expelled gas.

7. Two objects have an elastic collision. Before the collision they approach one another with a velocity of 45 m/s. With what speed will they be separating after the collision?

1. Calculate the magnitude of the impulse during the collision. 2. Calculate the magnitude and direction of the velocity of the 4.0 kg cart after the collision. 3. Calculate the mass m of the second cart

9. An athlete who is initially at rest in a squatted position jumps vertically upward and then lands going back to the original squatted position (ending at rest with the same center of mass height as at the start). The time period under consideration begins just before the athlete starts the upward motion and ends just after she has landed and comes to rest back in the squatted position. Compare the magnitude and directions of the impulse from the force of the ground on the athlete to the impulse from gravity on the athlete during this time period. Note: there are no other significant forces other than the ground and gravity acting on the athlete during this time period. of

20) A 17 kg child was going 3 m/s on skates when he collides with a 76 kg adult who was going -1.4 m/s. Both remain loose after the collision, which is elastic. How fast is the boy moving immediately after the crash?