## College Physics (7th Edition)

a). $0.154J$ b). $0.3087J$
a). $mgsin30^{\circ}=k\Delta x$ $\Delta x=\frac{mgsin30^{\circ}}{k}=\frac{1.5\times9.8\times0.5}{175}=0.042m$ Change in elastic potential energy of system = $\frac{1}{2}k(\Delta x)^{2}=0.154J$ b). System's change in potential energy =$mg\Delta xsin30^{\circ}$ $=1.5\times9.8\times0.042\times0.5=0.3087J$