1. Estimate the rate of speed (length per time) at which the hair on your head grows. Use your own experience as a guide for your answer. First express your estimate in inches per second and then in meters per second. Use scientific notation.
2. a) How many seconds are there in a year? b) If one micrometeorite (a cube with sides on the order of 1 μm) struck each square meter of the Moon each second, estimate the number of years it would take to cover the Moon with micrometeorites to a depth of one meter. Hint: Consider a cubic box, 1 m on a side, on the Moon, and find how long it would take to fill the box.