Question

Kinetic energy of a body of mass $0.1kg$ and momentum $20kgm{s}^{-1}$ is:

• A. $1kJ$
• B. $2kJ$
• C. $3kJ$
• D. $4kJ$

Answer 1

Answer: (B)

$2kJ$

Given, $p=20kgm{s}^{-1},m=0.1kg$

Kinetic energy, $K=\frac{1}{2}m{v}^2$ and momentum, $p=mv$

So, $K=\frac{1}{2}m\times {\left(\frac{p}{m}\right)}^2=\frac{p^2}{2m}$

$\therefore$ $K=\frac{{20}^2}{2\times 0.1}=2000J=2kJ$