Asemi-circle of radius 8 cm, rocks back and forth along a line. the distance between the line on which the semi-circle sits and the line above is 12 cm. as it rocks without slipping, the semi-circle touches the line above at two points. (when the semi-circle hits the line above, it immediately rocks back in the other direction.) what is the distance between these two points, in millimetres, rounded off to the nearest whole number

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.