# Simple Harmonic Motion and frequency of a spring

1. Mar 24, 2006

### kidia

I have one question here,I fail to understood what is Q of the system,is anybody has an ideal on this?

An object of mass 2 kg hangs from spring of negligible mass. The spring is extended by 2.5 cm when the object is attached. The top end of the spring is oscillated up and down in SHM with amplitude of 1 mm. The Q of the system is 15.

What is angular frequency for this system?

2. Mar 24, 2006

### Tom Mattson

Staff Emeritus
"Q" is just a symbol until it is given a definition. What does your book say about it? What do your class notes say about it?

The system will certainly not execute SHM. It is driven by gravity.

What have you tried so far?

3. Mar 24, 2006

### Firestrider

Sounds like Q is the frequency.

4. Mar 25, 2006

### nrqed

Q is the quality factor. it is an indirect measure of the damping. A large Q means that the damping is small, the oscillation takes a while to die off (assuming no external force of course).

If I recall, $Q = { \omega_d \over (b/m) }= {m \omega_d \over b}$

where $\omega_d \approx \omega_0$.
From the fact that spring extends 2.5 cm with a mass of 2 kg you can find the spring constant. So you know omega_0. Knowing Q then gives you a way to find the damping constant. I am not sure about the rest of the steps, though...

Pat