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

The book's kinetic energy when it slides away from the spring will be equal to the energy $U_s$ stored in the spring initially. We can find the speed of the book. $KE = U_s$ $\frac{1}{2}mv^2=\frac{1}{2}kx^2$ $v^2=\frac{kx^2}{m}$ $v=\sqrt{\frac{kx^2}{m}}$ $v=\sqrt{\frac{(1250~N/m)(0.040~m)^2}{0.500~kg}}$ $v = 2.0~m/s$ The book slides away with a speed of 2.0 m/s.