Arod of negligible mass is pivoted at a point that is off-center, so that length l1 is different from length l2 . the figures above show two cases in which masses are suspended from the ends of the rod. in each case the unknown mass m is balanced by a known mass, m1 or m2, so that the rod remains horizontal. what is the value of m in terms of the known masses?

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.