Question

How fast should a man of mass $60kg$ run, so that his kinetic energy is $750J$? Take $g=10m{s}^{-2}$

• A. $3m{s}^{-1}$
• B. $4m{s}^{-1}$
• C. $5m{s}^{-1}$
• D. $6m{s}^{-1}$

Answer 1

The correct option is C $5m{s}^{-1}$

Mass of a man, $m=60kg$
Acceleration due to gravity, $g=10m{s}^{-2}$
Kinetic energy, $KE=750J$
Let the mass of the man be $m$ and the velocity be $v$.
We know, $KE=\frac{1}{2}m{v}^2$
$\Rightarrow 750=\frac{1}{2}\times 60\times v^2$
$\therefore v=5m{s}^{-1}$