## Essential University Physics: Volume 1 (3rd Edition)

For a simple pendulum, we find: $T = 2\pi \sqrt{\frac{L}{g}}$ $T = 2\pi \sqrt{\frac{.8}{9.81}}=1.79428\ s$ For a physical pendulum $\underline{with\ a\ solid \ sphere\ attached}$, we know the following equation for period: $T = 2\pi \sqrt{\frac{\frac{2}{5}r^2+l^2}{gl}}$ $T = 2\pi \sqrt{\frac{\frac{2}{5}(.075)^2+(.8)^2}{9.81(.8)}}=1.80$ Using the equation for percent error, we find that the percent error is $\fbox{.147 percent}$