A body of mass m is projected with intial speed u at an angle `theta` with the horizontal. The change in momentum of body after time t is :-

Options

A. `mgu cos theta/sqrt2`
B. `mgu sin theta/sqrt2`
C. `mgu cos (90 - theta)sqrt2`
D. both 2 and 3

Answer

`(4)`

Explanation

`p = mg v_(y)`
`but v_(y)^(2) = u_(y)^(2) - 2g ( H)/2`
`v_(y)^(2) = (u^(2) sin^(2) theta)/2`
` v_(y) = (u sin theta)/(sqrt 2)`
`therefore P = (mg sin theta)/(sqrt2) = (mgu cos(90 - theta))/(sqrt2)`