Question

A football player kicked a ball with a velocity of $20m{s}^{-1}$ in a direction making an angle of ${60}^{\circ }$ with horizontal. Find the velocity with which he should run in the same direction so that the ball remains above this head.

• A. $15m/s$
• B. $10m/s$
• C. $20m/s$
• D. $15m/s$

Answer 1

The correct option is B $10m/s$

Let $v_{player}$ and $v_{ball}$ be the initial velocities of footballer and the ball respectively
The velocity with which he should run must be same as that of the horizontal component of the velocity of ball.
$\Rightarrow v_{player}=v_{ball}\cos \theta$
$=20\times \cos {60}^{\circ }=10m{s}^{-1}$