How Is Maximum Velocity Calculated in Simple Harmonic Motion?

[Pat2666]

http://img179.imageshack.us/img179/2245/springgraph226fe577uv1.jpg

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A 3.9 kg block is attached to a horizontal spring and undergoes simple harmonic motion on a frictionless surface according to the graph shown above.

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(a) What is maximum velocity of the box?
vmax = m/sec

HELP: How is the maximum velocity related to the applitude and the angular frequency of the oscillator?
HELP: How can you get the angular frequency and the amplitude from the above graph?

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(b) What is the mechanical energy of the box?
A = J

Okay, so at first I figured this problem wouldn't be too difficult, but I still couldn't figure it out lol I thought I was reading the period T and amplitude A correctly, but am I missing something? I have a feeling it has something to do with the fact it's a spring system. Anyways, here's what I tried below. I believe I'm using the correct equation for Vmax, but I must be getting either A, w or both incorrect.

Also, for part B I believe that would be the correct equation no? Since it's using Vmax PE would be zero.

Any help would be appriciated :)

http://img179.imageshack.us/img179/5518/06162008045940pmgf8.jpg

BTW - I got 1.57m/s for Vmax which was incorrect.

 

[alphysicist]

Hi Pat2666,

Your period is incorrect. (It should be in seconds, and the numerical factor does not match the graph.) Once that is corrected, I think you should get the right answers. What do you get?

 

[Pat2666]

Oh I see, I kept reading the x coordinate as cm for some reason! Thanks a lot, I totally overlooked that.

I got the right answers too :)

Vmax = 0.0157m/s
A = 4.81 * 10^-4 J