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!

Dynamics, Newton's laws, Problem with free body diagram and work

  1. Apr 2, 2013 #1
    1. The problem statement, all variables and given/known data
    A boy skateboards down a curved playground ramp. If we treat the boy and his skateboard as a
    particle of total mass m = 25:0 kg, he moves through a quarter-circle with radius R = 3:0 m. He
    starts from rest at point A and there is no friction.
    (a) Find his speed at the bottom of the ramp
    (b) Draw free-body diagrams for points A, B, C and D.
    (c) Find the normal force that acts on him at the bottom of the curve
    (d) Find work done by the normal force
    2. Relevant equations
    E=mgh
    E=(mv^2)/2
    3. The attempt at a solution
    I find answer for a, I use that change of potential energy is equal to kinetic. Also I done c because the normal force is equal change of potential energy. But i haven't got idea how to draw free-body diagrams and whywork done by normal force is equal 0 (Our teacher give us this answer)
     

    Attached Files:

  2. jcsd
  3. Apr 2, 2013 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Good.

    Not sure what you mean.

    Just label the forces acting on the particle, indicating their direction.

    At any point along the path, how does the direction of the normal force compare to the direction the particle is moving?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Dynamics, Newton's laws, Problem with free body diagram and work
Loading...