# Zero speed due to air resistance

Hello,

the other day i was playing pool, and i wondered about the following question: when a body is subject to air resistance, does it eventually get to zero speed? Or does it gradually slow down but never reaching 0 speed?

Excuse me if this question is nonsense, but when i heard about another subject, termodynamics, where the temperature of two bodies exchanging temperature never gets totally even, i thought about this situation with regards to speed.

Thanks in advance

## Answers and Replies

Im sorry but

I'm sorry, but i did not understand your answer. Im not used to the terminology you used. Do you mean that, in fact, the body wont reach zero velocity?

http://en.wikipedia.org/wiki/Terminal_velocity

The drag force increases with velocity, and if the object is accelerating (e.g under gravity) the velocity is increasing with time. So, after some time the acceleration due to the drag force comes to oppose the acceleration due to gravity; the object reaches zero acceleration, and the velocity can no longer increase- the object is said to have reached terminal velocity.

But that

But that only states that acceleration reaches 0, not that velocity will reach 0. In the situation in cause, there is not even an acceleration other than the air resistance, only an initial speed.

Khashishi
Science Advisor
Classically, I think the speed will approach 0 asymptotically. But in real like, the object will get slow enough that random thermal motion (Brownian motion) will take over.