posted by srikala .
a ball striking a horizontal plane with a velocity v rebounds with a velocity 256v/625 after 4th collision. the coefficient of restitution is?
(256/625)^1/4 = (16/25)^1/2 = 4/5
They deliberately picked a fraction for which both the numerator and deniminator are perfect fourth roots.
The answer is 4/5. Each bounce gives you 80% of the height of the previous bounce.