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Homework Help: Physics-please check answer (multiple choice question)

  1. Feb 24, 2014 #1
    Physics--please check answer (multiple choice question)

    1. The problem statement, all variables and given/known data
    Two objects have the same mass. One is travelling twice as fast as the other. The work that must be done to stop the faster object compared to the work required to stop the slower object is:

    a)two times greater
    b)the same
    c)four times greater
    d)half as great
    e)one quarter as great

    2. Relevant equations
    i think that KE=1/2mv^2 can help to understand the question

    3. The attempt at a solution
    I think that the answer would be c although I am not entirely sure. I used an example where the mass would be 2 kg and the speed of one mass is 4 m/s and the other is 8 m/s. As a result, I got 16 J for slower mass and 64 J for the faster mass. So I think that the work for the faster mass would be 4 times greater than the smaller one
  2. jcsd
  3. Feb 24, 2014 #2
    Yes, that's right. [itex]W = K \propto v^{2}[/itex], so if [itex]v[/itex] doubles, then [itex]K[/itex] quadruples.
  4. Feb 24, 2014 #3
    Your working looks good to me.
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