# Drag acting on ball the moment it bounces

• Darkmisc
In summary, the conversation discusses the velocity and drag of a light ball thrown at a wall, with the assumption that the wall is an xy-plane. It is determined that at the moment of collision, the ball has zero velocity in the z-axis due to changing direction, but is still moving in the x and y axes. At this moment, drag can be ignored in the z-direction, but is present in the x and y axes. The actual collision is quick and drag in any direction is negligible.

## Homework Statement

Suppose a very light ball is thrown at a wall.

The wall may be thought of as an xy-plane.

At the moment the ball hits the wall, does it have 0 velocity in the x, y and z directions?

Is drag on the ball (in each respective direction) small enough to be ignored at the moment the ball hits the wall?

D ~ (Av^2)/4

## The Attempt at a Solution

I think the ball momentarily has 0 velocity in the z-axis since the ball is changing direction along this axis.

I think the ball will be slowed in the x and y axes at the moment it hits the wall, but its velocity in these directions will not equal zero at that instant.

Therefore, drag can only be ignored in the z-direction.

The actual collision with the wall takes place very quickly. Drag in any direction is so small that it can be ignored.

Thanks.

Theoretically, is it correct to say that there is no drag in the z-axis at the moment of collision when the ball has zero velocity in the z direction? And that drag is present in the x and y axes at the moment of collision?