# Simple Harmonic Motion and frequency of a spring

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?

Tom Mattson
Staff Emeritus
Gold Member
kidia said:
I have one question here,I fail to understood what is Q of the system,is anybody has an ideal on this?

"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?

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.

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

What is angular frequency for this system?

What have you tried so far?

Sounds like Q is the frequency.

nrqed
Homework Helper
Gold Member
kidia said:
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?

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