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## Homework Statement

A smooth sphere falls vertically and strikes a fixed smooth plane inclined at an angle of ∅ to the horizontal.If the coefficient of restitution is (2/3) and the sphere rebounds horizontally,

Its speed before impact is u and after impact v

calculate the fraction of kinetic energy lost during impact.

## Homework Equations

## The Attempt at a Solution

Diagram of the question is attached to this post.

i = horizontal component vector and j = vertical component vector

Taking the inclined plane as the x axis

v, vcos∅i + vsin∅j ..... alternate angle to inclined angle

u, vcos(90 - ∅ )i - v sin(90 - ∅)j = usin∅i - ucos∅j

the I component remains the same

vcos∅ = usin∅

v = utan∅

vsin∅/(ucos∅) = 2/3 (v/u)tan∅ = 2/3 (utan∅/u)tan∅ =2/3

(tan∅)^2 = 2/3 tan∅ = (√6)/3

v = u(√6)/3

.5mu^2 - .5mv^2 = energy loss

.5mu^2 -.5m(6/9)u^2 = .5mu^2 - m(6/18)u^2 = .5mu^2 - (1/3)mu^2 = (1/6)mu^2

fraction of kinetic energy lost is 1/6

my book says the answer is 1/3 but I got 1/6. Any help would be appreciated.

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