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Homework Help: Conservation of momentum multiple choice

  1. Jan 4, 2010 #1
    Here is the question

    5. A long board is free to slide on a sheet of frictionless ice. As shown in the top view above, a skater skates to the board and hops onto one end, causing the board to slide and rotate. In this situation, which of the following occurs?

    A) Linear momentum is converted to angular momentum.
    (B) Kinetic energy is converted to angular momentum.
    (C) Rotational kinetic energy is conserved.
    (D) Translational kinetic energy is conserved.
    (E) Linear momentum and angular momentum are both conserved.

    The answer to the question I found is A. However, my teacher says it is E


    BCD are obviously wrong because its Kinetic - not conserved

    My problem with A is that it isn't fixed around a point, and it gives the implication that all momentum will be converted, which isn't - at least, to my thinking - true because it will move in a linear direction

    For E... Conservation of momentum is my only reasoning
  2. jcsd
  3. Jan 4, 2010 #2


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    What do you mean you 'found' A? How did you find it? Linear and angular momentum ARE conserved.
  4. Jan 4, 2010 #3
    I guess I should have clarified

    I found the answer online - its a former AP multiple choice my teacher gave us to prepare for a midterm

    The AP answer sheet says the answer is A
  5. Jan 4, 2010 #4


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    Ok, fair enough. Then that's a pretty sad AP answer sheet. If you don't have some other reason to believe it, then I would believe your teacher. Because your teacher is right.
  6. Jan 4, 2010 #5
    Thanks :)
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