# Homework Help: Circular Motion Problem

1. Mar 21, 2010

### cheerspens

1. The problem statement, all variables and given/known data

A space station has a radius of 200 meters. An astronaut has a mass of 55 kilograms and the station rotates at 1.5 rev/min. What is the period of rotation for the station?

2. Relevant equations
$$\tau$$=2$$\pi$$r/v
a=v2/r
Fg=mg
FNET=ma

3. The attempt at a solution
I think the FNET equation is Fsp=ma and I'm pretty sure you have to solve for $$\tau$$ but in order to do that I need to solve for a. How do I either find a velocity or acceleration to do this?

2. Mar 21, 2010

### kuruman

Time out. This is not a Newton's Second Law problem. Just think. If the station does 1.5 revolutions in one minute, what is the period, i.e. how long does it take to make one revolution?

3. Mar 21, 2010

### cheerspens

Would you just have to set it up as a proportion and find that it takes 1.5 seconds to make one revolution?

4. Mar 21, 2010

### kuruman

What kind of proportion? If (as you say) it takes 1.5 seconds to make one revolution, then it will make two revolutions in 3 seconds. But you are told that it makes 1.5 revolutions in one minute or 60 seconds. So what you say can't be right. Look at it this way: it makes 1.5 revolutions in 60 seconds. Can you find how many seconds for one revolution? It must be greater than 30 and less than 60.