# Homework Help: Mass in oscillating spring

1. Oct 2, 2008

### aleferesco

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

The position of a mass oscillating on a spring is given by x(t) = (18.3cm)cos[(2.35s^-1)t] .
What is the frequency of this motion?

2. Relevant equations

X= Amplitude x Cos (2pi/T x time)

3. The attempt at a solution

I know that frequency= 1/Period, im trying to use f= 1/(2.35s^-1) but it doesnt seem correct. Also i've tried multiplying the amplitude by 2.... f= 1/(18.3cm)x2

Thanks

2. Oct 2, 2008

### Rake-MC

so the form is $$x(t) = Acos( \omega t )$$

where $$\omega = 2 \pi f$$

Can you see how this helps you?

3. Oct 2, 2008

### aleferesco

so omega= 2.35s^-1

and so to find frequency I could just do f=2.35s^-1/2pi

I'm not sure about the reversing 1/1/T = s^-1

4. Oct 2, 2008

### Rake-MC

Sorry I don't understand what you're saying here, but yes:

$$f = \frac{\omega}{2\pi}$$

are you confused because omega is a reciprocal? That should play no part in exchanging frequency with period. So just follow that formula and you should be fine.

Note: I have not solved the problem numerically, but I can tell it's going to be a very small answer.

5. Oct 2, 2008

### aleferesco

Thank you very much!