1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Inclined plane with massless, frictionless winch

  1. Oct 30, 2008 #1

    A 100 kg box is pulled up an inclined plane by a massless, frictionless winch to which it is attached by a massless rope. The plane makes an angle of 45° with respect to the horizontal. The coefficient of friction between the box and the plane is μ = 0.25 (with μs = μk). The winch has a radius of 0.25 m and is turned at a constant angular velocity of ω = 3.14 radians/sec.

    How much work is done on the 100 kg box by the rope when the winch makes 10 complete revolutions?

    (a) 4380 J
    (b) 5235 J
    (c) 9262 J
    (d) 12531 J
    (e) 13620 J

    So I did d = [2(.25)(3.34)]10 since we need 10 rev. And then.......
    W = mgh + uNd
    W = mg(d sin 45) + u(mg cos 45)d
    but I'm not getting the right answer, I think I'm suppose to get 13620J, but how do I get that?

    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Oct 30, 2008 #2
    I'm not so sure that W = mgh + uNd
    Isn't mgh the gravitational potential that is gained by doing the work?

    I would sum up the forces that are opposing the pull of the rope (parallel to the plane) and multiply it by the distance it moves
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Inclined plane with massless, frictionless winch