A projectile is thrown upward with a velocity `v_(0)` at an angle `alpha` to the horizontal. The change in velocity of the projectile when it strikes the same horizontal plane is

Options

A. `v_(0) sin alpha` vertically downward
B. `2v_(0) sin alpha` vertically downward
C. `2v_(0) sin alpha` vertically upward
D. zero

Answer

B

Explanation

`Deltav = a Deltat` (as a = constant)
`= (-g hatj) ((2v_(0) sin alpha)/(g)) = (-2v_(0) sin alpha)hatj`
i.e., change in velocity is `2v_(0) sin alpha`, vertically downwards.