1. Limited time only! Sign up for a free 30min personal 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!

Work on a box

  1. Apr 1, 2010 #1
    1. The problem statement, all variables and given/known data
    A trunk of mass m = 2.3 kg is pushed a distance d = 187 cm up an incline with an angle of inclination q = 18.0° by a constant horizontal force P = 225 N (see figure). The coefficient of kinetic friction between the trunk and the incline is 0.22. Calculate the work done on the trunk by the applied force P.

    Calculate the work done on the trunk by the frictional force.

    [PLAIN]http://img706.imageshack.us/img706/9623/prob13a.gif [Broken]

    2. Relevant equations

    3. The attempt at a solution

    I solved for the work of the push, for the work of friction im doing this

    4.72N*1.87m=8.83 J, and because the work is on the negative direction of the movement its -8.83.

    Keeps saying my answer is wrong.
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Apr 1, 2010 #2
    A simple mistake. You're doing it all correctly, and you're going to hate this. You simply forgot to consider the component of P that is perpendicular to the ramp when calculating the frictional force. =/
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook