The work done in stretching a spring of natural length 25 $\mathrm{cm}$ and spring constant $50…
The work done in stretching a spring of natural length 25 $\mathrm{cm}$ and spring constant $50 \mathrm{Nm}^{-1}$ from $50 \mathrm{~cm}$ to $60 \mathrm{~cm}$ is