# Homework Help: Slightly confused regarding centripetal force, radius and frequency

1. Oct 27, 2011

### chris_0101

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

I have a question that is tied into my lab report regarding centripetal force. The question asks if the frequency of rotation were to increase how would the radius r and the centripetal force change?

2. Relevant equations

2$\pi$f = v/r

rearrange for r:

r = v/(2$\pi$f)

a = r(ω^2)

F_c = m*a
3. The attempt at a solution

By observing the formula rearranged for r, I believe that the radius is inversely proportional to frequency - so in this case as frequency increases, the radius will decreases.
Is this statement correct?

Since acceleration is dependent on radius and if the radius decreases so does the acceleration due to the direct proportionality between acceleration and radius. This ultimately means that the centripetal force is decreased as well when the frequency is increased
Is this statement also correct?

Thanks

2. Oct 27, 2011

### PeterO

How is this circular motion being achieved? - what is going in a circle.

The question can be easily interpreted if it is a satellite around the Earth.

Is this the standard prac where you rotate a rubber stopper on a fishing line with a bunch of washers hanging from the fishing line?

3. Oct 27, 2011

### chris_0101

I should have been more specific. Circular motion is achieved by an object spinning around an axis.

4. Oct 27, 2011

### PeterO

how is it attached to the axis? What is the object? What is it made of?