 #1
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 22
Homework Statement:
 See attached.
Relevant Equations:
 x(t)=Acos(wt+phi), v(t)=wAsin(wt+phi)
So first I found the total energy of the system by calculating the potential Energy, Ep=0.5k(l^2+l^2) and get 2.0475 (this part is right).
Then I find w using the period T=2pi/w, so w=2pi/1.21=5.1927
I also found the amplitude using E=1/2kA^2, so A=sqrt(2E/k)=0.212132
Now this is the part I think Im messing up. I go
0.15=Acos(phi) to find phi
Then x(t)=Acos(wt+phi) to find location. But this gives me the wrong answer of 0.14 when the answer should be 0.010.
Another thing that doesn't make sense to me is that I solved the amplitude using E=1/2kA^2, but when I try and solve the amplitude using 0.15=Acos(phi) and 0=wAsin(phi) I get an amplitude of 0.15, which is different.
Then I find w using the period T=2pi/w, so w=2pi/1.21=5.1927
I also found the amplitude using E=1/2kA^2, so A=sqrt(2E/k)=0.212132
Now this is the part I think Im messing up. I go
0.15=Acos(phi) to find phi
Then x(t)=Acos(wt+phi) to find location. But this gives me the wrong answer of 0.14 when the answer should be 0.010.
Another thing that doesn't make sense to me is that I solved the amplitude using E=1/2kA^2, but when I try and solve the amplitude using 0.15=Acos(phi) and 0=wAsin(phi) I get an amplitude of 0.15, which is different.
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