Question

A cannon ball of mass $500g$ is fired with a speed of $15m{s}^{-1}$. Find its kinetic energy.

• A. $7500J$
• B. $7.5J$
• C. $113.5J$
• D. $56.25J$

Answer 1

The correct option is D $56.25J$

$K.E=\frac{1}{2}\times m\times v^2$
$K.E=\frac{1}{2}\times m\times {15}^2$
Here mass is given in gram after converting that is $\frac{500}{1000}=0.5kg$ it becomes,
$K.E=\frac{1}{2}\times 0.5\times 225=56.25J$
Hence kinetic energy is $56.25Joule$.