2. A collar moves on a shaft under the action of force F. Force F remains horizontal throughout the motion of the collar. Determine an expression for the velocity of the collar as it reaches position B if it starts from rest at position A. Friction may be neglected.

A47.2 g block of copper whose temperature is 480 k is placed in an insulating box with a 91.8 g block of lead whose temperature is 200 k. (a) what is the equilibrium temperature of the two-block system? (b) what is the change in the internal energy of the two-block system between the initial state and the equilibrium state? (c) what is the change in the entropy of the two-block system? the heat capacities of copper and lead are 386 j/kg·k and 128 j/kg·k, respectively.