## Conceptual Physics (12th Edition)

Using the hint, set up ratios. $$\frac{1440 min}{360^{\circ}} = \frac{t_{unknown}}{0.53^{\circ}}$$ So the unknown time is 2.1 min. The sun moves a solar diameter in an overhead sky every 2.1 minutes. As explained on page 526, at sunset, refraction lets us see the sun even after it dips below the horizon. The setting sun takes longer than 2.1 minutes to vanish completely after the disk first touches the horizon.