Question

A particle projected from point O with velocity u in a direction making an angle $\alpha$ with the horizontal. At any instant its position is at point P at right angles to the initial direction of projection. Its velocity at point O is

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

Horizontal velocity at point 'O' = u cos $\alpha$

Horizontal velocity at point 'P' = v sin $\alpha$

In projectile motion horizontal component of velocity remains constant throughout the motion

$\therefore vsin\alpha =ucos\alpha \Rightarrow v=ucot\alpha$