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Homework Help: Problem involving incline, spring and friction

  1. Oct 15, 2005 #1
    I've been trying everything to solve this problem: It says:

    A block of mass m = 2.00 kg situated on a rough incline at an angle of = 37.0° is connected to a spring of negligible mass having a spring constant of 100 N/m. The pulley is frictionelss. The block is released from rest when the spring is unstretched. The block moves 18.6 cm down the incline before coming to rest. Find the coefficient of kinetic friction between block and incline.

    Please help me, I already tried to determine the force exerted by the spring in order to get the coefficent, but my answer is incorrect. i'm not sure how to relate all aspects of the problem. I tried to determine the PE of the spring, but how do i use that? (PE = 1/2kx^2)
    Last edited: Oct 15, 2005
  2. jcsd
  3. Oct 16, 2005 #2
    You can use energy conservation to solve this problem. While the block is at rest on the incline, it has potential energy from the spring .5*k*x^2 and from gavitational potential energy m*g*h (where h equals d*sin(angle) ). At the end it has only frictional energy u*m*g*d*cos(angle).

    The key to solving this is to first draw a diagram and then set initial energy equal to final energy. You should solve for u (the coefficient of friction) in this manner.
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