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Homework Help: Pushing a lawn mower, total force exerted?

  1. Jul 1, 2009 #1
    1. The problem statement, all variables and given/known data
    A person pushes a 13.0 kg lawn mower at constant speed with a force of 77.0 N directed along the handle, which is at an angle of θ = 49.0° to the horizontal.

    Calculate the force the person must exert on the lawn mower to accelerate it from rest to 1.8 m/s in 2.0 seconds with a retarding force of -50.5 N in the x direction.

    2. Relevant equations
    Using LaTeX Code: v^2 = v_0^2 + 2 a \\Delta x I found a = 0.81 m/s^2

    3. The attempt at a solution
    Using the acceleration of 0.81 m/s^2 times 13 kg I get F = 10.5 N, now I think I'm supposed to add the retarding force, but 61 N isn't correct.
    Did I miss something?
    Found the retarding force by finding the Fpcos(49) = 50.5 (in the x direction) Fp = 77.0 N.
    Beyond that I'm lost. Please help
  2. jcsd
  3. Jul 1, 2009 #2
    Nevermind, another problem helped me out, thank you! More will come!
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