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!

Find the force on an object on an inclined plane

  1. Aug 19, 2008 #1
    1. The problem statement, all variables and given/known data

    A body is projected up an inclined plane with a speed Vo. The inclination of the incline is [tex]\theta[/tex]. The surface of th incline is a tangent to a circle of radius R. Find the force acting on th object when it is at the top of the sphere provied that Vo= 2*the minimum velocity need to reach the top of the sphere.
    The length of incline = L
    Assume that the block does not lose contact with the track.
    3. The attempt at a solution
    The minimum velocity required, as I calculated was:
    [tex]\sqrt{2g[R(1-cos \theta)+ L sin \theta}[/tex] which was correct.
    But the Force I calculated was diffrent.

    At the top of the phere, the velocity will become Vo/2. Why oesnt (mV^2)/R give me the correct answer? as the body perform circular motion. Help me please.
  2. jcsd
  3. Aug 20, 2008 #2
    Re: Force

    I am posting a picture of the situation. Please help me now.
    Last edited: Aug 20, 2008
  4. Aug 20, 2008 #3


    User Avatar
    Science Advisor
    Homework Helper

    Re: Force

    The minimum velocity required to reach the top satisfies (1/2)mv0^2=mgh (where h is the total height of the top of the sphere) - use conservation of energy. If you leave with twice that velocity your energy at the top is (1/2)m(2*v0)^2-mgh. Equate that to kinetic energy at the top and solve for velocity. You DON'T arrive with half the initial velocity.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?