The speed of a falling stone

[jakesi]

If I dropped a stone from 20,000 ft what is the max speed it will get to before it hits the ground?

[the evil dad]

120 m.p.h. as this is the terminal velocity of an object in the earth's atmosphere.

[Electromech]

It depends on the size and shape of your stone. Objects in free fall high in the atmosphere accelerate and then settle to a final (terminal) velocity according to air drag. For a solid object like a stone the bigger it is the faster it falls, because air drag is what slows it down and this becomes proportionately less with increase in size. The smoother, and more streamlined, the stone is will also help. Examples are: a large, very dense, streamlined solid object dropped from 20,000 feet will be approaching the speed of sound (760 mph) when it hits; a person spreadeagled will reach 120 mph, or 180 mph in a headfirst dive. A stone will be somewhere in between these limits.