Finding amplitude? SHM problem

1. Dec 12, 2009

jvick717

Finding amplitude??? SHM problem

1. The problem statement, all variables and given/known data
A 245 g mass attached to a horizontal spring oscillates at a frequency of 3.70 Hz. At t =0s, the mass is at x= 4.40 cm and has v_x = -25.0 cm/s.
Determine:

2. Relevant equations
I got the first two
The Period= .27027 s
The Amplitude=? m rounded to 5 sig figs
The Phase Constant=? rad rounded to 5 sig figs

3. The attempt at a solution

I tried using the equation (x)t=Acos($$\omega$$t+$$\phi$$)
and plugged in t=0 and .0440m for x(0) so the answer i got was .0440m but this is wrong. and i can't attempt the phase constant yet because i need the Amplitude for that. Any help is appreciated thanks.

2. Dec 12, 2009

diazona

Re: Finding amplitude??? SHM problem

Yes you can. You're off to the right start, but you'll need another equation to determine the phase constant. Hint: there's another value you're given in the problem that you haven't used. What can you do with it?

3. Dec 14, 2009

jvick717

Re: Finding amplitude??? SHM problem

I'm guessing that the velocity has something to do with it and maybe the other equation for velocity v(t)= -A$$\omega$$sin($$\omega$$t+$$\phi$$)??