The planet Mercury has a mass that is 5.00% of that of Earth, and its gravitational acceleration is gmercury = 3.70 m/s2. a) How long does it take for a rock that is dropped from a height of 2.63 m to hit the ground on Mercury? b) What is the ratio of the time it takes the rock to hit the ground on Mercury to the time it takes the rock to hit the ground on Earth (tM/tE)? c) From what height would you have to drop the rock on Earth so that the fall-time on both planets is the same?