Question

Why is the average velocity of the molecules in a gas is zero?

Answer 1

Reasons why the average velocity of the molecules in a gas is zero:

1. The velocity of the molecules is a vector quantity.
2. In a container, some molecules go in the right(+) direction and some molecules go in the left(-) direction.
3. If the container is at rest then the total velocity of molecules going in the right direction will be equal to the total velocity of the molecules going in the left direction.
4. These opposite going molecules will cancel the velocity of each other and the average velocity of the molecules in a gas will be zero.

Thus the average velocity of the molecules in a gas is zero.