We know that when a ball is dropped from height
h , it strikes the surface with speed
v=√2gh It is given that the ball is dropped from height
5m . Substituting this value and value of acceleration due to gravity in the formula we get
v=√2×10×5 ,
v=√100 ,
v=10m∕s We also know that when a ball rebounds with speed
u , the height it reaches is given by
H= It is given that the ball reaches height
1.8m on rebound. Substituting this value and value of acceleration
due to gravity in the formula, we get
1.8= u2=36 ,
u=6m∕sHence the ball loses its velocity by
4m∕s on rebounding.
The fractional loss can be calculated by dividing the loss in velocity with initial velocity, i.e. velocity with
which it strikes the floor i.e
10m∕s Hence, fractional loss in velocity
=, fractional loss in velocity
=.