Question

A force of magnitude $25N$ acting on a body of mass $2kg$ doubles its kinetic energy to $200J$. The displacement of the body during this interval is:

• A. $2m$
• B. $3m$
• C. $4m$
• D. $5m$

Answer 1

The correct option is C $4m$

Given: force, $F=25N$, mass, $m=2kg$,
change in kinetic energy = final kinetic energy - initial kinetic energy $=(200-100)J=100J$
Let the displacement of the body be $s$ and the work done be $W$:

According to work-energy theorem:
Work done = change in kinetic energy of the body.
$\therefore W=100J$

We know,
​​​​​​Work done = Force $\times$ displacement.
$\Rightarrow s=\frac{W}{F}=\frac{100}{25}=4m$

Therefore, the displacement of the body is $4m$.