1.

A smooth sphere is moving on a horizontal surface with velocity vector 2hati+2hatj immediately before it hits a vertical wall. The wall is parallel to hatj vector and the coefficient of restitution between the sphere and the wall is e = 1//2. The velocity vector of the sphere after it hits the wall is

Answer»

`HATI-HATJ`
`-hati+2hatj`
`-hati-hatj`
`2hati-hatj`

Solution :`hatj` component i.e., component of VELOCITY PARALLEL to wall remains unchanged while `hatj` component will become `(-1/2)(2hati)or -hati`. Therefore velocity of the sphere after it HITS the wall `-hati+2hatj`.


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