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: Basic Physics Problem. Please Help

  1. Jul 3, 2009 #1
    A 71.8-kg skier coasts up a snow-covered hill that makes an angle of 25.1 ° with the horizontal. The initial speed of the skier is 8.84 m/s. After coasting a distance of 2.10 m up the slope, the speed of the skier is 3.41 m/s. (a) Find the work done by the kinetic frictional force that acts on the skis. (b) What is the magnitude of the kinetic frictional force?

    Part a= -1761 J

    I Just cant figure out how to find part b
  2. jcsd
  3. Jul 3, 2009 #2
    What is the definition of work done?
  4. Jul 3, 2009 #3
    Work done is equal to KE+PE so kinetic energy final + mgh- kinetic energy intial+ mgh where kinetic energy is 1/2mvsquared
  5. Jul 3, 2009 #4
    There is another definition of work done which says
    [tex]W=r \cdot F[/tex]

    Try it now.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook