A body (solid sphere) of mass m makes an elastic collision with another idential body at rest. Just after collision the angle between the velocity vector of one body with the initial line of motion is `15^(@)` then the angle between velocity vector of the other body with the initial line of motion is

Options

A. `75^(@)`
B. `60^(@)`
C. `45^(@)`
D. `30^(@)`

Answer

A

Explanation

Since collision is elastic `(1)/(2)mv^(2)=(1)/(2)mv_(1)^(2)+(1)/(2)mv_(2)^(2)`
`impliesv_(1)^(2)+v_(2)^(2)=v^(2)` …(i)
And momentum conservation given `mvecv=mvecv_(1)+mvecv_(2)`
`impliesvecv_(1)+vecv_(2)vecv` ..(ii)f ltbr. Equation (i) and (ii) shows that angle between the velocity o both bodes after collision is `90^(0)` thus angle made by another body `=90-15=75^(0)`