## Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)

The energy stored in a spring is $\frac{1}{2}kx^2$, where $k$ is the spring constant and $x$ is the stretch distance. $\frac{1}{2}kx^2 = 2.0~J$ Let's suppose the spring is stretched a distance of $3x$. We can find the energy $E$ stored in the spring. $E = \frac{1}{2}k(3x)^2$ $E = (9)(\frac{1}{2}kx^2)$ $E = (9)(2.0~J)$ $E = 18~J$ The energy stored in the spring will be 18 J.