Find Frequency and Amplitude from Max Velocity and Accn

  • Thread starter rocapp
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  • #1
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Homework Statement


See attached screenshot


Homework Equations


Vmax=Aω
ay=-ω2A

The Attempt at a Solution


The given max velocity is 1.2 m/s, so

1.2 = ωA

Ay = -ω^2A

1.2/A = -√260/A
A = 0.005
 

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Answers and Replies

  • #2
haruspex
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1.2/A = -√260/A
Parentheses would help, and don't worry about the sign because you only want the magnitude.
A = 0.005
A little inaccurate. How many significant figures do you think you should provide?
This is just part B. Any problem with part A?
 
  • #3
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I tried 0.006, but it didn't work either. I am not sure what to do for part A at all.
 
  • #4
haruspex
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I tried 0.006, but it didn't work either.
You didn't answer my other question: how many significant figure do you think you should give in the answer? Why are you only giving one?
I am not sure what to do for part A at all.
You already have an equation you can solve for ω.
 
  • #5
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There should be two significant figures, but my homework doesn't mind a little inaccuracy. I'm still having difficulty with part A.

Since

A = (ω)/(vmax)

and

A = (amax)/(ω2)

then

ω/vmax = amax/(ω2)

Plug in knowns:

260/(ω^2) = ω/1.2
ω3 = 312
ω = 6.78
ω = 2πf
f = 1.08

This is not correct, though. And I do not know why.
 
  • #6
haruspex
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There should be two significant figures, but my homework doesn't mind a little inaccuracy. I'm still having difficulty with part A.
OK, but I think it's worth trying 0.0055
Since A = (ω)/(vmax)
No - try that one again. (What dimension would frequency/speed have?)
 
  • #7
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0.0055 was incorrect.

frequency/speed would be m/sec^2... OH!

So A = (vmax)/ω, correct?
 
  • #8
haruspex
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0.0055 was incorrect.

frequency/speed would be m/sec^2... OH!

So A = (vmax)/ω, correct?

Yes.
 
  • #9
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I'm still getting 0.0055 for amplitude. Any ideas?
 
  • #10
haruspex
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0.0055m looks right to me.
 
  • #11
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Well the homework software is counting it wrong. Thanks for the help!
 

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