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Homework Help: Anybody please help

  1. Sep 29, 2008 #1
    1. The problem statement, all variables and given/known data
    A wedge with an inclination of angle theta rests next to a wall. A block of mass m is sliding down the plane, as shown. There is no friction between the wedge and the block or between the wedge and the horizontal surface. (Intro 1 figure) what is the magnitude of the force of the wall exerts on the wedge?

    2. Relevant equations

    I know that the sum of all forces is mg sin theta. and i know that the normal force between the block and wedge is mgcos theta. Please does anyone know the answer

    3. The attempt at a solution
  2. jcsd
  3. Sep 29, 2008 #2
    the sum of all forces is mg
  4. Sep 29, 2008 #3
    f net would actually be mgsin theta. Im doing the problem right now on an online program and for that part of the problem it said that i got it right. so those are the knowns, mgsintheta for the net forces and mgcos theta for the normal force between the block and the wedge.
  5. Sep 29, 2008 #4
    I think it depends on what you are calling 'all' the forces.

    the only outside force acting on the system is gravity and gravity doesnt care about thewedge or anything else. it just acts downward
  6. Sep 29, 2008 #5
    i just rearranged some equations and found that the answer was mgcos@sin@
  7. Sep 29, 2008 #6
    most problems like this consider the wedge to be immobile. therefore one would normally consider the force to be mg sin theta. in this problem the wedge is not immobile.
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