Aball is dropped from rest at the top of a 6.10 m
tallbuilding, falls straight downward and collides inelastically
withthe ground, and bounces back. the ball loses 10% of itskinetic
energy every time it collides with the ground. howmany bounces can
the ball make and still reach a windowsill that is2.38 m above the
ground?

n = 5 approx

Explanation:

If v be the velocity before the contact with the ground and v₁ be the velocity of bouncing back

= e ( coefficient of restitution ) =

and

h₁ is height up-to which the ball bounces back after first bounce.

From the two equations we can write that

So on

= .00396

Taking log on both sides

- n / 2 = log .00396

n / 2 = 2.4

n = 5 approx

the bal will not change its velocity.