Physics - W.E.P. Question with Solution | TestHub

The potential energy stored in a spring stretched by a distance $x$ is given by $U=\frac{1}{2}k{x}^2$.

For $x_1=1\text{cm}$, the potential energy is $U_1=\frac{1}{2}k(1{)}^2=\frac{1}{2}k$.

For $x_2=4\text{cm}$, the potential energy is $U_2=\frac{1}{2}k(4{)}^2=16\left(\frac{1}{2}k\right)=16U_1$.

The difference between the energies is $U_2-U_1=16U_1-U_1=15U_1$.

Answer: $15U_1$