Which is true? earth. a. to see a total solar eclipse, you must travel to one particular small spot on b. from the penumbral part of earth's shadow, the sun is totally obscured c. at earth's poles, day and night are caused by earth's rotation. d. acceleration has units m's, and technically, the direction must also be given. e. the planets follow elliptical orbits with the sun at the center.

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.