Question

A body of mass $5kg$ has momentum of $10kgm/s$. When a force of $0.2N$ is applied on it for $10$ seconds, what is the change in its kinetic energy?

• A. 1.1 J
• B. 2.2 J
• C. 3.3 J
• D. 4.4 J

Answer 1

Answer: (D)

$u=\frac{p}{m}=\frac{10}{5}=2m/s,a=\frac{0.2}{5}m/s^2$
$v=u+at=2+\frac{0.2}{5}\times 10=2.4m/s.$
$\Delta K=\frac{1}{2}m{v}^2-\frac{1}{2}m{u}^2=\frac{1}{2}\times 5\times {\left(2.4\right)}^2-\frac{1}{2}\times 5\times 2^2$
= 4.4 J.