# College Physics 2.5 – The Earth’s Average Speed & Velocity

## Solution:

### Part A

The average speed of the earth is equal to the distance traveled divided by the time.

$\displaystyle \text{Average speed of the Earth}=\frac{\text{Distance Traveled}}{\text{Total time of Travel}}=\frac{2\pi \text{r}}{\text{t}}$

$\displaystyle =\frac{2\pi \left(1.50\times 10^{11}\text{ m}\right)}{365.25\:\text{days}}\times \frac{1\:\text{day}}{24\:\text{hours}}\times \frac{1\:\text{hour}}{3600\:\text{sec}}$

$\displaystyle =2.99\times 10^4\:\text{m/s}$

### Part B

After a period of 1 year, the planet Earth has already returned to its original position with respect to the Sun. This means that we do not have any displacement. Therefore, the average velocity is zero.

$\displaystyle \text{Average velocity}=0\:\text{m/s}$