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Amount of time for a half period to occur

by Capncanada
Tags: occur, period, time
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Capncanada
#1
Oct25-11, 03:22 PM
P: 53
1. The problem statement, all variables and given/known data

A mass-spring system has k = 105 N/m and m = 1.75 kg.

If it is undergoing simple harmonic motion, how much time does it take the mass to go from x = A to x = 0?

2. Relevant equations

T=2pi*sqrt(m/k)

3. The attempt at a solution

Tried plugging in the values for the equation I gave to find T, then cutting it in half to find the amount of time the question asked for, but it's not the correct answer.
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vela
#2
Oct25-11, 03:25 PM
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What exactly is one cycle? If you understand that, you'll see why your answer is wrong. It may help to look at a diagram that shows one period in your textbook.
Capncanada
#3
Oct25-11, 03:25 PM
P: 53
When the mass goes into the spring and back?

ehild
#4
Oct25-11, 03:26 PM
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Amount of time for a half period to occur

Sketch the x(t) function for a full period and see.

ehild
vela
#5
Oct25-11, 03:32 PM
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Quote Quote by Capncanada View Post
When the mass goes into the spring and back?
Yes. So in one cycle, if it starts at x(0)=A, it ends at x(T)=A, but more important, what does x(t) do in between? As ehild suggested, plot x(t) for one cycle.
dextercioby
#6
Oct25-11, 03:33 PM
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Who's A and can you link it to T ? EDIT: So A's the amplitude...
Capncanada
#7
Oct25-11, 03:36 PM
P: 53
Uhh x goes to A? Which equation can I use to solve for that? x=Acos(ωt)?

Sorry I'm braindead been studying all morning I just want this homework done.
ehild
#8
Oct25-11, 03:54 PM
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Quote Quote by Capncanada View Post
Which equation can I use to solve for that? x=Acos(ωt)?
Yes. x = A cos (2pi* t/T). How does it look like? What is x at t=0, t=T/8, T/4, ...

ehild
Capncanada
#9
Oct25-11, 10:20 PM
P: 53
So I can plug in x as A so that A cancels out here and then solve for t where T = 1/2?
ehild
#10
Oct26-11, 02:45 AM
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Quote Quote by Capncanada View Post
So I can plug in x as A so that A cancels out here and then solve for t where T = 1/2?
Is T=1/2???????


Would you please show me a cosine function? Please!!!!

ehild


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