# The ISS orbits around Earth, at an altitude of 350. km. What is the speed? What is the period? How many orbits will complete per day?

##### 1 Answer

and it will complete 16 orbits per day.

#### Explanation:

For this solution we will make the (reasonable) assumption that the ISS exhibits uniform circular motion.

In that case we can use this equation for the speed:

where

But two of the variables in that equation are unknowns (

where

and

**First work out the radius of orbit.**

**Now calculate the time period.**

We can use that in the first equation above to **calculate the speed:**

**We can write the period in minutes or hours to make it more practical:**

**Lastly, we want to know how many orbits the ISS will make per day.** Divide the total time of one day (24 hours) by the time for one orbit in hours: