# Simple Spring & Angular Fequency Problem

1. Jul 29, 2015

### shanepitts

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

2. Relevant equations
Fs=-kx

3. The attempt at a solution
In image below

This question might be amateurish

Why does my answer equate to negative angular frequency when the given result is positive?

2. Jul 29, 2015

### Qwertywerty

Firstly , mg = (k1 + k2)x and not it's negative .

Secondly , what have you done here ?
Why have you equated mg to keqx ? This only gives you the equilibrium position .

Correct derivation would be - find keq , then write the formula for w interms of k and m .

Hope this helps .

3. Jul 29, 2015

### shanepitts

Thank you, it helps. But I am wondering how do I find
keq?

4. Jul 29, 2015

### Nathanael

There is a certain spring constant, keq, such that if we put a single spring with that spring constant in place of the other two springs, it would have the same effect.

So if you displace the mass by Δx, then the two springs exert a total force of F on the mass. That means (by the above definition) the effective spring constant is F/Δx.

So now try to find this total force F (from the springs) in terms of the given spring constants and Δx.

5. Jul 31, 2015

Thank you