Question

The kinetic energy of a body of mass $3kg$ and momentum $2Ns$ is

• A. $1J$
• B. $\frac{2}{3}J$
• C. $\frac{3}{2}J$
• D. $4J$

Answer 1

Answer: (B)

$\frac{2}{3}J$

Given,

Mass, $m=3kg$

Momentum, $P=mv$

Velocity, $v=\frac{P}{m}=\frac{2}{3}m{s}^{-1}$

Kinetic energy, $\frac{1}{2}m{v}^2=\frac{1}{2}\times 3\times {\left(\frac{2}{3}\right)}^2=\frac{2}{3}J$

Hence, kinetic energy is $\frac{2}{3}J$