Question

A body of mass $60kg$ has the momentum $3000kgm{s}^{-1}$. Calculate the kinetic energy.

• A. $7.5\times {10}^{1}J$
• B. $7.5\times {10}^{2}J$
• C. $5\times {10}^{4}J$
• D. $7.5\times {10}^{4}J$

Answer 1

The correct option is D $7.5\times {10}^{4}J$

$K.E=p^2/2m$
p = 3000 kg m/sec and m = 60 kg
This is the relation obtained from two formulae,
$p=m\times vandK.E=\frac{1}{2}\times m\times v^2$
Hence $K.E=\frac{p^2}{2m}=\frac{{3000}^2}{2\times 60}J$
$K.E=75\times {10}^{3}J$.