# Spectroscopy hookes law, derivation?

1. Jun 1, 2015

### popopopd

hi, i am a lillte confused why the equation for hookes law is

1/(2pi*c)*sqrt(k/m_reduced)?

where does c come from?

http://www.massey.ac.nz/~gjrowlan/intro/lecture5.pdf

- slide 8.

also, is there any particular reason why we use reduced mass?

Last edited by a moderator: Jun 2, 2015
2. Jun 2, 2015

### Staff: Mentor

This is not a Hooke's law, rather a result you can get by solving the motion equation for an oscillator assuming it obeys Hooke's law (so it is a harmonic oscillator).

I don't see where the c comes from either. Using reduced mass makes calculations much easier for the system made of two oscillating objects (as compared to the system containing one object oscillating around some equilibrium position).

3. Jun 2, 2015

### popopopd

Ah I found it. by definition wavenumber is v/c and that gave the equation 'c'

4. Jun 3, 2015

### Staff: Mentor

They stated ν is frequency, not wavenumber.

5. Jun 4, 2015

### popopopd

yeah thanks, they did. I think they are wrong.