Explanation:
For a body of mass \(m\) on applying a force \(F\)
for a time \(\Delta t\), the body suffers a velocity change
\(\Delta v\), then
\(F=m a=m \dfrac{\Delta v}{\Delta t}\)
\( \Rightarrow F\Delta t = m\Delta v\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(1)\)
So, we have
\(F=x N, \Delta t=2 s, v_{1}=2 m s^{-1}\)
\( \Rightarrow {v_2} = 3\;m{s^{ - 1}},\,\,m = 0.5\;kg\)
Substituting these values in Eq. (1), we get
\( \Rightarrow x = \frac{{0.5}}{2} = 0.25\;N\)