# Homework Help: Find mass of skaters

1. Nov 16, 2011

### hinamori88

1. The problem statement, all variables and given/known data
Two identical ice skaters are holding onto opposite ends of a very long spring with a spring constant of 650 N/m. While spinning in a circle, the skaters frequency of revolution is measured to be 0.85 Hz. What is the mass of the skaters?

2. Relevant equations
F = kx

3. The attempt at a solution
F = (650 N/m)x ?

Last edited: Nov 16, 2011
2. Nov 17, 2011

### ehild

Remember, circular motion is the resultant of two perpendicular SHM with the same frequency and amplitude and phase difference of pi/2.

ehild

3. Nov 17, 2011

### hinamori88

Oh so then u use the equation
f=(1/2∏)√(k/m)
And the m needs to be 2m...ok got it!

Thank you!!

4. Nov 17, 2011

### ehild

No, m is not twice that of one skater-just the opposite.

Both skaters spin along the same circle. The situation is the same for each of them as if there was a pole at the centre, and half of the spring connected to the pole with one end and the other end to the skater. What is the spring constant of a halved spring?

ehild