Problem and Data three masses conected m1= 800g, m2 =1100g m3=1200g. m2 rest on a table of coefficient μ=0.345. m1 and m3 hang vertically over frictionless/massless pulleys. The system is released from rest. Whats the velocity of m3 after falling 60.0cm P.S "i know this system can be solve with finding tension and such, but i have to use energy conservation method." 2. Relevant equations W(work)= ΔK+ΔUg(potential gravitational)+ΔUs(Spring energy) 3. The attempt at a solution The velocity for m3 would be the same for all three masses because they are connected by a string. There's no k (initial) and spring energy involved. This is what i have gotten so far; I made a system of equations for each body: Δy i defined as the change of height for potential energy. m1; W= (1/2)m1v^2+ m1gΔy m2; W= (1/2)m2v^2 m3; W=(1/2)m3v^2-m3gΔy (the minus from negative displacement in height(Δy)) Im not sure about the following, i think im missing something; " *I also know that the system is losing energy by the interaction of M2 w/ the surface of the table...friction. so friction(f)= N(normal)*μ(K). In other words: f=m2*g*μ and Work is also =f*r(displacement by the force)* cos (θ) θ being the angle between the force and the displacement." I'm just not sure how to related the energy lost W on all three bodies Thanks for any input or help you guys can provide on my problem.