Setup: A 100 kg rock is dropped from rest from a height of 10,000 km above the Earth's surface at the Equator. Air resistance is neglected.
Observations:
- The acceleration of gravity on the rock is small compared to g = 9.80 m/s2 for most the rock's decent since the acceleration of gravity goes as one over distance squared.
- The rock's velocity just after it is dropped is small because its acceleration is only about 1/10 g at the start.
- The Space Shuttle typical height is only about 400 km. At this altitude g = 8.68 m/s2. Saying that the astronauts are weightless is misleading. They are in free fall.
- If the rock is truly dropped from rest, then it the Earth would rotate out from underneath the drop point. If the rock were rotating at the same rate as the Earth (so that the rock was stationary relative to the point on the Earth's below the rock initially) the rock's motion would be that body in a elliptical gravitational orbit. The rock would still not land on the point below it initially.
- See Long Distance Rock Drop IP simulation or Long Distance Rock Drop Problem.