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**HELP-SEE LAST POST-I HAVE NO IDEA WHY THIS IS WRONG (SEE LAST POST)**

## Homework Statement

A spring with spring constant 230 N/m vibrates with an amplitude of 12.0 cm when 0.380 kg hangs from it.

(a) What is the equation describing this motion as a function of time? Assume the mass passes through the equilibrium point, toward positive x (upward), at t = 0.120 s.

x = A cos(omega t + phi)

**A = 12 cm**

W = 24.6 s^-1

W = 24.6 s^-1

Phase Shift (phi)= ___________

(b) At what times will the spring have its maximum and minimum lengths? (Consider only the first instances after t = 0.)

_____________maximum s

_____________minimum s

(c) What is the displacement at t = 0?

_____________

(d) What is the force exerted by the spring at t = 0?

____________

(e) What is the maximum speed?

_____________

When is it first reached after t = 0?

_____________

## Homework Equations

x = A cos(omega t + phi)

[tex]\sqrt{k/m}[/tex]

## The Attempt at a Solution

Okay, so I've been working on this problem, and I got the first two parts pretty much no problem. A was practically given to you, and W was found using the formula [tex]\sqrt{k/m}[/tex]. No problems there-I've bolded the two answers that I have correct.

Now, the next part is what really gets me. If I plug everything in to find phi, (the phase shift) for part a, the third answer, I don't know the x, and I don't know how to find it.

Thank you so much for the help!

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