1. The problem statement, all variables and given/known data In the system shown, the block M (mass of 15.65 kg) is initially moving to the left with a speed of 3.4 m/s The mass of m is 8.26 kg and the coefficients of friction are μs=0.411 and μk=0.304. The string is massless and the pulley is massless and frictionless. How fast will M be traveling when m has fallen through a height h=2.47 meters? diagram: http://is.byu.edu/courses/univ/694820121008/media/8_problem_blockmass.jpg 2. Relevant equations Ef - Ei = Kf - Ki + Uf - Ui = -fkd + ∑ W_otherforces K = 1/2mv^2 U=mgy 3. The attempt at a solution Since M does not have any change in potential energy, but it is acted on by a tension force, I got Ef - Ei = 1/2mvf2 - 1/2mvi2 = -fkd + T where fkd = μkMgd and T = (( μk+1)Mg)/(1+M/m) I solve for vf but keep getting the wrong answer. The answer should be about 4.32 m/s What am I doing wrong?