Question

At what height above the ground must a mass of $5kg$ be to have its P.E. equal in value to the K.E. possessed by it when it moves with a velocity of $10m/s$? (Assume $g=10m/s^2$)

• A. $1m$
• B. $5m$
• C. $10m$
• D. $50m$

Answer 1

The correct option is B $5m$

Let height be $h$.
So, $PE$ at that height $=mgh$
$KE$ of the mass when moving with velocity $10m/s$ is $\frac{1}{2}m{v}^2$
Since, $PE=KE$
$mgh=\frac{1}{2}m{v}^2$

Putting values we get:
$10\times h=50$
$h=5m$