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Length of a Pendulum

  • #1

Homework Statement



A 319g ball is tied to a string. It is pulled to an angle of 7.60 degrees and released to swing as a pendulum. A student with a stopwatch finds that 14 oscillations take 13.0s.
What is the length of the string?

Homework Equations


I have already tried using T = 2pi sqrtL/g, but that does not give me the right answer.


The Attempt at a Solution

 

Answers and Replies

  • #2
11,280
4,741
Show your work so we can see what you did.
 
  • #3
13 oscillations/14 seconds = 1.07 for T, and 1/1.07 = 0.928s for f.
Then I tried T = 2pi sqrt L/g, so 1.07 = 6.28 sqrt L/9.8m/s, then divided each side by 6.28 and got 0.170 = sqrt L/9.8, then squared each side, so 0.029 = L/9.8, then solve for L = 0.2842m, which is wrong according to MasteringPhysics.
 
  • #4
11,280
4,741
How far off is your answer?

It looks okay to me. Is the g value for earth or some other planet?
 
Last edited:
  • #5
I figured it out...I had period and frequency backwards
 

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