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Homework Help: Mass on an inclined plane w/ FRICTION (use work energy theorem)

  1. Nov 16, 2011 #1
    Mass on an inclined plane with friction!
    There is a mass at the bottom of an inclined plane. It travels with an initial velocity up the inclined plane at an angle θ. There is a coefficient of friction on the ramp. How far up the ramp will the mass go before stopping? What is the speed of the block when it returns to the bottom of the ramp? What percent of the initial total mechanical energy was lost during the mass's trip (going up and then back down?
    m=5 kg
    vo=40 m/s
    S=the distance you are looking for
    Coefficient of friction (μ) = 0.15

    Work energy theorem=mg(hf-ho) + 1/2 m (vf^2-vo^2) +fs

    i set up the work energy theorem and simplified it down to "work=mghf-1/2mvo^s+μ
    mgs" and solved for s
    and then i used "work= -mgho + 1/2mvf^s +μ
    mgs to solve for vf
    i honestly had no clue what to do for the third part of this problem

    I dont think my answers are right bc i got 0.598 m fr the first part and 2.23 m/s fr the second part...and i couldnt figure out the third part

    Help would be appreciated. Thank u very much to all!
    Last edited: Nov 16, 2011
  2. jcsd
  3. Nov 16, 2011 #2


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    Homework Helper

    I think this should be 0 = mg*h - ½m⋅Vo² + μ*Fn*s
    since no work is done except the included friction work; it has initial velocity but the final velocity is zero, h is the height it goes up. Express h in terms of s and the angle of the ramp. You will solve for s to find the answer. The normal force, Fn needs to be figured out from the force of gravity and the angle.
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