Question

A particle of mass $1kg$ is subjected to a force which varies with distance as shown in the figure. If it starts its journey from rest at $X=0m$. Find its velocity at $X=15m$.

• A. $0$
• B. $20\sqrt{3}m{s}^{-1}$
• C. $20\sqrt{2}m{s}^{-1}$
• D. $20m{s}^{-1}$

Answer 1

The correct option is D $20m{s}^{-1}$

The work done W equals the area under the force vs. distance graph.

$W=2\times \frac{1}{2}\times 20\times 5+5\times 20=200J$

work done equal to the kinetic energy.

$\Rightarrow W=\frac{1}{2}M{v}^2$

$\Rightarrow \frac{v^2}{2}=200$

$\Rightarrow v=20m{s}^{-1}$

Hence D option is correct .