AIIMS 2017 Physics Question Paper for free online practice with solutions

Components of velocity before and after collision parallel to the plane are equal,
v sin60°=u sin30° .......(1)
Components of velocity normal to the plane are related to each other
v cos60°=eu(cos30°) ........(2)
⇒ cot60°=e cot30° ⇒e=

cos60°

cot30°

⇒e−

1 √3

√3

⇒e=

1

3

.