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!

Homework Help: Finding work done by friction on a box

  1. Nov 25, 2015 #1
    A box of mass
    m = 59.0 kg
    (initially at rest) is pushed a distance
    d = 83.0 m
    across a rough warehouse floor by an applied force of
    FA = 204 N
    directed at an angle of 30.0° below the horizontal. The coefficient of kinetic friction between the floor and the box is 0.100. Determine the work done by the force of friction

    2. Relevant equations
    W = fdcosΘ
    3. The attempt at a solution
    I used the two above equations and I found that the applied force of friction would be 57.82 because that is .1*59*9.8 and then if you put that into the first equation, the work would be 57.82*83*cos30 which equals 4156.108 and then since it is opposite the applied force, it would be -4156.108. At least I thought. That's wrong and I don't know why. Please help!
  2. jcsd
  3. Nov 25, 2015 #2
    But in this problem, the normal force is larger than the weight.
  4. Nov 25, 2015 #3
    The vertical component of F add to weight.
    Remember when resolving vector, here force, noted all the components. Here the X and Y components.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted