Question

A body of mass $5kg$ initially at rest is subjected to a force of $20N$. What is the kinetic energy acquired by the body at the end of $10s$

Answer 1

$force=mass\times acceleration$

$a=4\frac{m}{s^2}$

we know that,

$K.E=\left(\frac{1}{2}\right)\times m\times v^2$

To find $v$

$v=u+a\times t$

$v=0+(4\times 10)$

$v=40\frac{m}{s}$

$K.E=\left(\frac{1}{2}\right)\times 5\times {40}^2$

So,
$K.E=4000J$