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Math Help - Calculating work and force on an angle

  1. #1
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    Calculating work and force on an angle

    Example problem: A refrigerator weighing 175lbs is on a 50' ramp. The ramp has an incline of 15*. Find the magnitude of force required to keep the refrigerator from sliding down the ramp and the work required to push the refrigerator up the ramp.

    The example says w=FxDcos75 so work =2265ft lbs. I dont really understand how they got this formula.

    How do I find out the force to keep the fridge from sliding down the ramp?
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  2. #2
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    e^(i*pi)'s Avatar
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    To stop it sliding down the ramp you need to apply an equal, but opposite force.

    W = Fs\cos \theta is a standard formula (s is distance) but usually you get a flat plane so \cos(\theta) = \cos(0) = 1

    If you draw a diagram you should be able to find the angle to be 90-15=75 degrees.

    I'm just wondering how your book gets 2265, it works if F=175 but surely F=175g ?
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