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Homework Help: Basic Physics Question

  1. Nov 1, 2006 #1
    Hi everyone! This is my first post so I thought it appropriate to start with a basic question and not give u guys a hard time :) ehehe

    So imagine u have 1 box resting on a larger box. A force is applied to this larger box and the smaller box moves with the larger box without slipage.

    My question is, if I were to draw up the FBD, what forces are being applied on the small box apart from Fn and Fg?

    Cheers
     
  2. jcsd
  3. Nov 1, 2006 #2
    Well isn't that it?? Apart from a rediculously small amount of drag, which force do you suppose is keeping the small box from sliding off the larger one? that's your hint..
     
  4. Nov 1, 2006 #3
    Well, I am thinking apart from Fn + Fg there is a friction force keeping that small box stationary on top of the larger box. If that is the case there must be a balancing force because technically the small box is relatively stationary. So this means that we also have the applied force Fa on the small box too?

    This results in 4 forces: Fn, Fg, Fa, Ff

    Am I on the right track?

    o:)
     
  5. Nov 1, 2006 #4
    You are right to think that there is an equal/opposite of the static friction on the small box, but that force acts on the big box.
    So, a revised list would be:
    Fn,Fg,Fs where Fs=force of static friction
     
  6. Nov 1, 2006 #5
    Makes sense... thanks a bunch :)
     
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