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Homework Help: A 6kg box is placed on a 32degree frictionless ramp. Find accel. of the box.

  1. Sep 29, 2009 #1
    I have the solution to the problem but I don't get the part how you rotate the axes and then solve from there.

    For example in the x direction
    Fx = max

    +mg sin32 = max

    Fx = Force in x direction
    ax = acceleration in the x direction

    Can someone explain this?
  2. jcsd
  3. Sep 30, 2009 #2


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    You're taking the component of the weight vector down the ramp. That is the force that accelerates the box.
  4. Sep 30, 2009 #3


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    Welcome to PF!

    Hi Kaxa2000! Welcome to PF! :smile:
    I'll just add that you shouldn't think of it as a rotation …

    everything stays as it is, and you simply choose to take components in whatever direction is most conveniento:)

    for example, you could use horizontal and vertical components …

    but that would give you two equations :redface:, while choosing along-the-ramp and normal gives you only one relevant equation, which is much easier! :wink:
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