Question

A particle is projected from a point $O$ with velocity $u$ at an angle of ${60}^o$ with the horizontal. When it is moving in a direction at right angles to its direction at $O$, its

• A. $\frac{u}{3}$
• B. $\frac{u}{2}$
• C. $\frac{2u}{2}$
• D. $\frac{u}{\sqrt{3}}$

Answer 1

The correct option is D $\frac{u}{\sqrt{3}}$

when particle is projected with some angle with horizontal, then acceleration acting is only is in vertical direction so component of velocity in horizontal direction will be same.

[angle made by particle with horizontal will be 30 when it will be perpendicular to its initial position.]

let final velocity of particle is $v_f$ then $v_{f}Cos30=uCos60$

$v_f=\frac{u}{\sqrt{3}}$.