A projectile is projected at `10ms^(-1)` by making an angle `60^(@)` to the horizontal. After sometime, its velocity makes an angle of `30^(@)` to the horzontal . Its speed at this instant is:

Options

A. `(10)/(sqrt(3))`
B. `10sqrt(3)`
C. `(5)/(sqrt(3))`
D. `5sqrt(3)`

Answer

A

Explanation

As the velocity makes an angle of `30^(@)` with horizontal, so the horizontal component of velocity at the instant will be `v cos 30^(@)`.
`rArr v cos 30^(@) = 5 rArr v = (5)/(cos 30^(@)) = (5)/(sqrt(3)//2) = (10)/(sqrt(3))ms^(-1)`