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Homework Help: Force on a Frictionless Surface

  1. Sep 24, 2009 #1
    1. The problem statement, all variables and given/known data
    In the figure, a crate of mass m = 111 kg is pushed at a constant speed up a frictionless ramp (θ = 30°) by a horizontal force F . The positive direction of an x axis is up the ramp, and the positive direction of a y axis is perpendicular to the ramp. (a) What is the magnitude of F ? (b) What is the magnitude of the normal force on the crate?

    2. Relevant equations

    3. The attempt at a solution

    For part A, I got 628.67 N which is correct.

    I do not have part B, but I do have some other information that I found, which is correct.

    Gravitational Force along x-axis is -544.455 N

    Fx component of the applied force is 544.45 N

    Fy component of the applied force is -314.341 N

    Y component of the gravitational force is -943.023 N

    Acceleration components are zero.

    And the normal force of the crate is in the positive direction of the y-axis.

    Anybody know how to get part B?
  2. jcsd
  3. Sep 25, 2009 #2

    Andrew Mason

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    Science Advisor
    Homework Helper

    Do a free body diagram for the crate. Is the crate accelerating? What does that tell you about the net force (the sum of all forces) acting on the crate? You know the gravitational force and horizontal force F. Is there any other force besides the normal force of the ramp on the crate?

  4. Sep 25, 2009 #3
    No, there is just the normal force. I got the normal force to be 1257.36 I believe.
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