Momentum review

A girl is standing still in the middle of a baseball field. The girl catches the baseball and begins to move in the same direction as the thrown ball. What type of collision is being described?

• elastic - the girl moves opposite the direction of the thrown ball

• elastic - the girl moves in the same direction of the thrown ball

• inelastic - the girl moves in the same direction of the thrown ball

• inelastic - the girl moves opposite the direction of the thrown ball

A train car has a mass of 10,000 kg and is moving at +3.0 m/s. It strikes an identical train car that is at rest. The train cars combine. What is the magnitude of the final velocity of the combined cars?

• 1.5 m/s

• 3.0 m/s

• 6.0 m/s

• 0 m/s

A 0.25 kg baseball is in contact with a bat for 0.0075 s and exerts a force of 18,500 N. What impulse is delivered to the ball?

• 4600 kg m/s

• 140 kg m/s

• 33 kg m/s

• 74000 kg m/s

An object with a mass of 1.5 kg changes its velocity from +15 m/s to +22 m/s during a time interval of 3.5 seconds.

What impulse was delivered to the object?

• 25 N s

• 3.0 N s

• 11 N s

• 56 N s

How does an airbag help protect a passenger in a car following a car accident?

• It shortens the stopping time and this increases the force

• it shortens the stopping time and decreases the force

• it increases the time and this decreases the stopping force

• it increases the stopping time which increases the stopping force

Which equation best describes the law of conservation of momentum?

• p_i = p_f

• p_i < p_f

• p_i > p_f

• p_i + p_f = 0

Object A and object B are moving with the same momentum. Which of the following statements must be true?

• The products of their mass and velocity

  must be equal.

• They must have the same velocity, but

  not necessarily the same mass.

• They must have the same mass, but

  not necessarily the same velocity.

• They must have the same mass and

  velocity.

A 7.0 kg bowling ball traveling at 2.0 m/s collides with a stationary 0.5 kg beach ball in an elastic collision. The bowling ball leaves the collision with a velocity of 1.5 m/s traveling in the same direction as the beach ball.

• 3.5 m/s

• 2.0 m/s

• 1.0 m/s

• 7.0 m/s