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Homework Help: How would you go about finding the force of this object?

  1. Oct 31, 2012 #1
    A wrench slides off a tilted shelf, although if a force of 1.6N is applied opposite the wrench's motion the wrench will slide down the shelf with a constant velocity. If the shelf is 1.2m long, what is the work done by the applied force on the wrench?
    This is what I did:
    w=(1.6N)(1.2m)= and got 1.92 J
    On the worksheet it said that I have to multiply it also by cos 180, but i'm not understanding where they got cos 180 from. Can someone please explain?
  2. jcsd
  3. Oct 31, 2012 #2
    The force is being applied in the opposite direction of the displacement for work. Therefore, you have to use 180 degrees instead of 0 degrees.
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