Question

A ball of mass m is dropped onto a floor from a certain height. The collision is perfectly elastic and the ball rebounds to the same height and again falls. Find the average force exerted by the ball on the floor during a long time interval.

Answer 1

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ANSWER::

Let height be 'h' from where the ball of mass m is dropped onto a floor.

Before collision => v₁ = √(2gh) and then v₁ = 0

After collision => v₂ = - √(2gh) and then v₂ = 0

Rate of change of velocity , F = [m x 2√(2gh)] / t

Now , v = √(2gh) , s = h , v = 0

v = u+at

√(2gh) = gt

t = √(2h/g)

Total time = 2√(2h/g)

F = [m x 2√(2gh)] / [2√(2h/g) ] = mg

Hope it helps!