# What Forumla?

1. Jan 11, 2006

### StaticShock

What formula should I use for this question? I'm thinking hook's law, but It doesnt seem to fit.

A mass is attached to a spring that has a constant of 100 N/m. The mass vibrates with a frequency of 2 Hz.

I have to find the value of the mass and how far it streaches. I know I can use hook's law for the streaching part, but I am unsure of how to carry out this problem.

2. Jan 11, 2006

### andrewchang

$$T = \frac {1}{f} = 2 \pi \sqrt {\frac {m}{k}}$$

3. Jan 11, 2006

### StaticShock

Are you sure thats the right one? I mean, it looks as if its finding period not frequency. So wouldnt it be F=1/t= 1/2 pi Sqroot k over m?

4. Jan 11, 2006

### andrewchang

that's just the general equation. it's up to you to do the algebra that will give you the value that you want.

5. Jan 11, 2006

### StaticShock

well based on some information I found, the square root of the mass over K is equal to the equasion of L over g. If all things are reletive then, I should be able to switch it as i would when finding frequency.

Last edited: Jan 11, 2006
6. Jan 11, 2006

### StaticShock

However, the second question may not have anything to do with hooke's law at all. It may just be F= 1 over 2pi Sqrt g over L

But I am unsure if g is to be used based on earth's speed of gravity or if I am on the right track at all.

7. Jan 11, 2006

### andrewchang

why do you do this? the equation i gave you has frequency, mass, and the spring constant. you know two of these, so just solve for the mass.