2.3 Exercise 18

The planetary model of the atom pictures electrons orbiting the atomic nucleus much as planets orbit the Sun. In this model you can view hydrogen, the simplest atom, as having a single electron in a circular orbit $1 . \text{06} \times \text{10}^{- \text{10}} \text{ m}$ in diameter. (a) If the average speed of the electron in this orbit is known to be $2 . \text{20} \times \text{10}^{6} \text{ m}/\text{s}$, calculate the number of revolutions per second it makes about the nucleus. (b) What is the electron’s average velocity per revolution?