AP Physics B : Understanding Momentum and Impulse

Study concepts, example questions & explanations for AP Physics B

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Example Questions

Example Question #62 : Newtonian Mechanics

Two astronauts, Ann and Bob, conduct a collision experiment in a weightless, frictionless environment. Initially Ann moves to the right with a momentum of , and Bob is initially at rest. In the collision, the two astronauts push on each other so that Ann's final momentum is  to the left. What is Bob's final momentum?

Possible Answers:

 to the right

 to the right

 to the left

 to the right

 to the left

Correct answer:

 to the right


Apply conservation of momentum before and after the collision.


Taking left to be the negative direction, and noting that Bob's initial momentum is 0 since he is at rest, we can use the provided information to see that  .

Solving for , we get . Since this answer is positive, Bob's momentum is in the positive direction (to the right).

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