A ball of mass 200g is projected with a density of `30m//s` at `30^@` from horizontal. Using the concept of impulse, find change in velocity in 2s. Take `g=10m//s^2`.

Answer

B

Explanation

In air, a constant force `(= weight =mg)` will act on the ball. Therefore, the linear impulse can be obtained directly by multiplying this constant force with the given time interval. Further, this linear impulse is equal to the change in linear momentum. Thus,
`J=Fxxt=Deltap=mDeltav`
`implies Deltav=(t/m)F=(t/m)mg`
`=gxxt=(10m//s^2 dowonwards)(2s)`
`=20m//s` (downwards)