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Homework Help: Free-Body Diagram

  1. Oct 21, 2007 #1
    1. The problem statement, all variables and given/known data
    A large box containing your new computer sits on the bed of your pickup truck. You are stopped at a red light. The light turns green and you stomp on the gas and the truck accelerates. To your horror, the box starts to slide toward the back of the truck. (Assume that the truck is accelerating to the right.)

    Draw clearly labeled free-body diagram for the truck. (The bed of the truck is not frictionless.)

    2. Relevant equations
    N normal force
    Wt Weight of the truck
    fk is friction force of the box on the truck bed
    Froad is the reaction force to the tires backward push
    nb is the reaction to the normal force on the box from the truck

    3. The attempt at a solution

    I got N going upward
    Wt going downward
    nb going downard
    fk going to the right (forward)
    Froad going to the right (forward)

    However, it's not the correct answer. Anyone could explain to me what I got wrong here?

  2. jcsd
  3. Oct 23, 2007 #2
    No one knows the answer or can lend me a hand with this?
  4. Oct 23, 2007 #3
    Normal force of the box by the truck bed should be going up.
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