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Homework Help: Overall Force

  1. Apr 26, 2010 #1
    1. The problem statement, all variables and given/known data

    Annie uses her 1.50 x104 N Subaru wagon to drag a 2.00 x 103 N crate of mulch from the nd of her driveway. She uses a rope to attach the crate to the rear bumper of her wagon and she configures this connection so that her car will exert a horizontal force on the crate. She then gets into her car and accelerates it (and the crate) forward a steady rate of 2.00 m/s2. While Annie is thus dragging the crate along her driveway, a steady 1200 N frictional force acts on the crate, opposing its motion.

    2. Relevant equations

    Questions I'm having difficulty are:
    1. The magnitude of the overall force which the ground exerts on Annie's car equals _____
    (the answer is 1.57 x 104 N)

    2. The overall force which the ground exerts on Annie's car is directed _____
    (answer is above the positive x direction)

    3. The attempt at a solution

    1. I would assume I need to add the weight of Annie's car and add that to the weight of the crate both which I get a combined 17000 N. This value does not match the correct answer.
    2. I cannot find the answer to #2 until I have found the value for #1. From then on, I do not know how to figure it out.

    Please help me! Thanks!
  2. jcsd
  3. Apr 27, 2010 #2


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    Science Advisor
    Homework Helper

    hi starprincess! :wink:
    No, the weight of the crate has nothing to do with the force which the ground exerts on Annie's car … try the vertical component again.

    For the horizontal component, use good ol' Newton's second law for the car-and-crate combined …

    what do you get? :smile:
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