1. The problem statement, all variables and given/known data A block of mass 15g enters the bottom of a circular, vertical track with a radius R = 0.5m at an initial velocity of 4/ms. If the block loses contact with the track at an angle of = 130, what is Wk, the work done by kinetic friction? http://img94.imageshack.us/img94/1760/problem1t.png [Broken] 2. Relevant equations Work Energy theorem: (1/2)m(Vfinal)^2 - (1/2)m(Vinitial)^2 Work = Force * Displacement 3. The attempt at a solution The 3 forces acting on the block: normal force, gravity, and friction. http://img43.imageshack.us/img43/442/fbodydia.png [Broken] Before block loses contact, Gravity has a y-component of .5(sin(40)) Normal force has a y-component of .5(sin(40)) and an x-component of .5(cos(40)) The initial kinetic energy is (1/2).015(4)^2 which equals .012 Joules. Not really sure where to progress from here.