# Circular Motion - Quick Help Please!

1. Oct 18, 2005

### dekoi

Andy and Bella move in circular paths about a common point with the same constant angular velocity $$\omega$$. Bella's mass is half the mass of Andy. The distance, where Andy is from the centre of the circle, is twice the distance of Bella. Who of the two will experience the greater magnitude of the centripetal force, $$F_c$$?

The answer given is that they will experience the SAME force. However, I found otherwise.

Since $$F_c=m\omega^2R$$

$$F_a=m_a\omega^2R_a$$ and $$F_b=m_b\omega^2R_b$$

The ratios I obtained were: $$m_b=\frac{m_a}{2}$$ and $$R_b=\frac{R_a}{2}$$.

When I find the ratio, I get:
$$\frac{F_a}{F_b}=\frac{m_a\omega^2R_a}{m_b\omega^2R_b}=\frac{m_aR_a}{\frac{m_a}{2}\frac{R_a}{2}}$$

My end result will be the value, 4, which is not 1, which I am looking for in order for the forces to be equal.

Is there a problem with my method, or is the answer given the wrong answer?

2. Oct 18, 2005

### Staff: Mentor

I agree with your analysis. The answer is wrong. (Or someone messed up the problem statement.)

3. Oct 18, 2005

Thank you.