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: Mechanical Energy problem

  1. Jan 22, 2008 #1
    [SOLVED] Mechanical Energy problem

    1. The problem statement, all variables and given/known data
    http://img517.imageshack.us/img517/7201/dynamics3oi8.jpg [Broken]

    2. Relevant equations
    [tex]E_{m}=E_k + E_p[/tex]

    3. The attempt at a solution
    I think that the answer to the problem is c), because as the object is moving up, it is slowing down because it has to work against friction and gravity. Also, as the object moves up, it gains height, and therefore gains potential energy. Am I right?
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Jan 22, 2008 #2
    Can anyone help?
  4. Jan 22, 2008 #3
    If there's a net force up the ramp then it has to be accelerating, and therefore KE is increasing.
  5. Jan 22, 2008 #4
    we dont know where the net force is pointing though, because we dont know the magnitude of all the forces.

    the answer depends on whether the forces cause the ball to move up or down the ramp. either way the kinetic energy will be increasing since it was motionless a moment before.

    the mechanical energy will be increasing/decreasing depending which way the ball moves.
  6. Jan 22, 2008 #5
    Thanks dylan.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook