JEE Main Physics question
A ball falling from a height of 10 m rebounds from a hard floor. If it loses 20% energy in the impact, then the coefficient of restitution is
Answer: (A)
Solution
Since 20% of the energy (and hence height, as U=mgh) is lost: h₂ = 0.8h₁. The coefficient of restitution is e = √(h₂/h₁) = √0.8 ≈ 0.89.