A projectile is projected with a speed `u` at an angle `theta` with the horizontal. What is the speed when its direction of motion makes an angle `theta//2` with the horizontal

Options

A. `(u cos theta)/(2)`
B. `u cos theta`
C. `u (2 cos (theta)/(2) - sec (theta)/(2))`
D. `u (cos(theta)/(2) - sec(theta)/(2))`

Answer

C

Explanation

In a projectile motion, the horizontal component of velocity remains same.
`v cos ((theta)/(2)) = u cos theta`
`v = (u cos theta)/(cos ((theta)/(2))) = (u (2 cos^(2)(theta)/(2) - 1))/(cos(theta)/(2))`
`u (2 cos(theta)/(2) - sec(theta)/(2))`