A body of mass `0.5 kg` is projected under the gravity with a speed of `98 m//s` at an angle of `30^(@)` with the horizontal. The change in momentum (in magnitude) of the body when it strikes the ground is

Options

A. `98 N - s`
B. `49 N - s`
C. `196 N - s`
D. `24.5 N -s`

Answer

B

Explanation

`vec(u)_(1) = u cos theta hat(i) + u sin theta hat(j)`
`vec(u)_(2) = u cos theta hat(i) - u sin theta hat(j)`
`Delta vec(p) = vec(p)_(2) - vec(p)_(1) = - 2 mu sin theta hat(j)`
`|Delta vec(p:} = Delta p = 2 mu sin theta = 2 mu sin 30^(@)`
` = 2 xx (1)/(2) xx 98 xx (1)/(2) = 49 N - s`