1. The problem statement, all variables and given/known data 2 boxes are connected by a massless rope. the system is frictionless m1 = 3kg m2 = 5kg http://img388.imageshack.us/img388/2033/problemwr4.jpg [Broken] Find m1's speed when it is 1.8 m above the ground. 2. Relevant equations K = 0.5mv^2 U = mg delta y 3. The attempt at a solution v1=v2 obviously also, delta y of m1 = 1.8, whereas delta y of m2=-1.8 At the beginning: Etot = K1 + K2 + U1 + U2 since K1, K2 and U1 are = 0, Etot = U2 = m2*g*5 = 25g When m1 is 1.8 meters above the ground: Etot = K1+K2+U1+U2 25g = 0.5m1v2+0.5m2v2+1.8m1g-1.8m2g solving for v gives 8.37, but the answer is 2.97 can anyone help me find what is wrong in my reasoning?