1. The problem statement, all variables and given/known data An object of mass 0.2 kg with initial velocity 4.8 m/s slides a horizontal distance of 3.0 m before coming to rest (final velocity is 0 m/s). What is the coefficient of kinetic friction on the surface? 2. Relevant equations K + U - W(other) = 0 ...conservation of energy 3. The attempt at a solution I have delta-K = 0 - (1/2)(0.2)(4.8)^2 = -0.48 J delta-U is zero since there is no change in y W(other) would be just the work done by the frictional force f(k). f(k) <= (mu)kn....where n-mg = 0... so n = mg = 1.96 N ....f(k) <= (mu)k*1.96N W = F*d.... F = f(s)..... since U = 0 ..... K - W(other) = 0..... K = W(other) = -0.48 J F*d = -0.48 J (mu)k*1.96N*3.0m = -0.48 J Solving for (mu)k I get (mu)k = 0.0816. From the back of the book I know this is wrong, the given answer is 0.392. What am I doing wrong? Thanks!