Halliday, Resnick & Walker — Kinetic Energy and Work: Problem 29

29 In the arrangement of Fig. 7-10, we gradually pull the block from $x = 0$ to $x = +3.0 \text{ cm}$, where it is stationary. Figure 7-28 gives the work that our force does on the block. The scale of the figure's vertical axis is set by $W_s = 1.0 \text{ J}$. We then pull the block out to $x = +5.0 \text{ cm}$ and release it from rest. How much work does the spring do on the block when the block moves from $x_i = +5.0 \text{ cm}$ to (a) $x = +4.0 \text{ cm}$, (b) $x = -2.0 \text{ cm}$, and (c) $x = -5.0 \text{ cm}$?