# forces acting on a ball dropped from 4m ? Are the forces balanced or unbalanced?

Where would the arrows go on a diagram?
Original post by Kbeen
Where would the arrows go on a diagram?

Are you drawing the diagram as the ball is in their air? Or as it hits the ground?

If the forces are balanced, then the ball will maintain its state of motion (i.e. it will have a constant velocity, which may be zero). Is the ball falling at a constant velocity? Or is it accelerating towards the ground?

In terms of forces acting on the ball, is the ball in a vacuum, or do we need to consider drag (air resistance)?
Yes uk drawing it at the top of its max bounce,
How would I know if the forces are balanced, the ping pong ball is simply dropped from a 4m height, what forces would act on it?
Original post by Kbeen
Yes uk drawing it at the top of its max bounce,

Original post by Kbeen
How would I know if the forces are balanced, the ping pong ball is simply dropped from a 4m height, what forces would act on it?

Bounce? Bounce? When did the ball start to bounce? The title of the thread says it was "dropped".

The instant the ball is first dropped the only force acting upon is that due to gravity. As it accelerates towards the ground drag increases (assuming we're not in a vacuum, which is why I asked the question), until it reaches terminal velocity - at which point the Fdrag and Fgravity are equal and opposite (i.e. balanced) at it remains in a constant state of motion: falling at a constant velocity. I obviously don't know what "level" or question this is (GCSE, A level, etc.) so don't know whether my mentioning drag and terminal velocity is over-complicating things. If it is, just ignore drag.

If we're talking about the result of a bounce, then on it's way up it will be decelerating - meaning the forces acting upon it must be unbalanced. Once it reaches "the top of its max bounce" it is momentarily stationary before it begins to fall again. At that instant the only force acting on the ball is gravity, which causes the ball to accelerate downwards again.

(I'm assuming the ball is dropped and bounces vertically; your mention of it being a ping pong ball introduces the possibility that it might be bouncing at an angle, or that spin might be involved.)