What is the Amplitude in an SHM Problem?

[jvick717]

Finding amplitude? SHM problem

Homework Statement

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:

Homework Equations

I got the first two
The Period= .27027 s
The Angular Frequency= 23.248 rad/s
The Amplitude=? m rounded to 5 sig figs
The Phase Constant=? rad rounded to 5 sig figs

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.

 

[diazona]

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

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?

 

[jvick717]

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+$$\phi$$)??