Energy and Momentum Chapter Test

Car A is moving to the right with a speed of 18 m/s and car B is moving to the left with a speed of 11 m/s. Both cars have a mass of 990 kg. What is the total momentum of the system consisting of cars A and B? (You may define positive direction to be to the right)

• 6600 kg⋅m/s

• 0.0 kg⋅m/s

• -6900 kg⋅m/s

• 6900 kg⋅m/s

A bowling ball has a mass of 4.9 kg and is traveling with a velocity of 24 m/s down the lane. How much momentum does it have?

• 580 kg m/s

• 1400 kg m/s

• 4.9 kg m/s

• 120 kg m/s

A 1.0 kg block sliding on a frictionless surface is moving with an initial velocity of 9.0 m/s. An impulse is applied to the block as shown on the graph. What is the block's speed at time t = 6 s?

• 11 m/s

• 17 m/s

• 25 m/s

• 7.0 m/s

Jimi (80 kg) and Tony (100 kg) stand motionless on ice skates, facing each other at arm's length on a smooth, frozen pond. Which of the following actions will give Tony the greatest speed?

• Jimi pushes Tony with 60 N of force for 0.2 s.

• Jimi pushes Tony with 250 N of force for 0.04 s.

• Tony pushes Jimi with 100 N of force for 0.1 s.

• Tony pushes Jimi with 200 N of force for 0.08 s.

A spring-loaded ballistic cart measuring 30 kg is in contact with a second 84 kg cart. The carts are initially at rest on a level surface. The spring is released and the lighter cart is observed to move at +0.17 m/s afterward. What is the velocity of the other cart?

• -0.17 m/s

• -0.061 m/s

• -0.48 m/s

• 0.48 m/s

A model rocket with an initial mass of 3.0 kg is launched horizontally by burning and expelling 560 g of fuel with a velocity of 180 m/s. What is the velocity of the rocket after the fuel is expelled? (Assume the propellant is expelled instantaneously.)

• 41 m/s

• 0.78 m/s

• 210 m/s

• 34 m/s

A motionless 130 kg astronaut is holding a 14 kg tool while on a spacewalk. To get moving, the astronaut throws the tool forward at a speed of +4.5 m/s. How fast does the astronaut move backward?

• 0.48 m/s

• 0.035

• 4.5

• 0.11 m/s

A 1000 kg car with 280 kg of passengers and cargo is moving at 61 m/s. Suddenly, the driver applies the brakes and the car skids to a stop. What happens to the momentum that the car (and its contents) had before braking?

• It is transferred to the pavement (and the Earth).

• It is turned into sound.

• It is lost as heat.

• It is transferred to the driver.

Two friends wearing frictionless rollerskates are facing each other within arm's reach. Jimi pushes gently on his friend Tony's upraised palms. What happens?

• Both Jimi and Tony remain motionless, unless they push on each other with enough force.

• Jimi rolls away from Tony, and Tony remains motionless.

• Both Jimi and Tony remain motionless.

• Jimi and Tony roll in opposite directions.

A sphere of mass 7 kg is moving at 5 m/s to the right until it smacks into a second stationary sphere of mass 5 kg. After the collision, both spheres travel to the right: the first sphere at 0.833 m/s, and the second sphere at 5.83 m/s. What kind of collision took place?

• This is an inelastic (but not perfectly inelastic) collision.

• This situation is impossible.

• This is a perfectly inelastic collision.

• This is an elastic or nearly elastic collision.