if terminal velocity is the fastest an item can free fall, then if you were to shoot an item downwards, faster then it’s terminal velocity, would it slow down, or maintain that same speed? If it does slow down, what force is slowing it? Would it work the same way in a vacuum?

Question

if terminal velocity is the fastest an item can free fall, then if you were to shoot an item downwards, faster then it’s terminal velocity, would it slow down, or maintain that same speed? If it does slow down, what force is slowing it? Would it work the same way in a vacuum?

In: Physics

Answer 1

It might help to think of “terminal velocity” as “the point where an object is going fast enough through air that the air pushing back stops its acceleration”.

In other words, the force of air on an object is a function of how fast the air is moving past it. So as the difference in speeds increase (either through faster air or faster object), that force increases. If the speed is increasing because of gravity (a relatively constant force), eventually the force of the air caused by that speed will match the force of gravity.

So if you start with a higher speed? Then the force of the air will be greater, which will slow the object down until gravity catches up to keep the object falling.

And while all of that assumes air is relatively constant, if you change the air’s density it will also decrease how much force it can cause. This decreases all the way down until it reaches 0 in a vacuum. So in a vacuum, that force of air acting against gravity won’t be doing anything, translating into an infinite terminal velocity.