Thinking about Newton’s First Law. Why does a water powered rocket come back down? a
The rocket would like to keep on going, but gravity is an unbalanced force that pulls it down.
b
Things are lazy, and the rocket does not want to go anywhere.
c
The parachute that is on the rocket has a large enough area to make it stay in the air
d
There is not enough fuel in the rocket. Despite balanced forces, it has to come down.

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.