# Pendulum Question

1. Oct 31, 2014

### michaeltozer13

1. The problem statement, all variables and given/known data
a)The angle that the string of a long pendulum makes with the vertical is shown as a function of time. What is the angular frequency of the pendulum?
b)What is the amplitude of the pendulum's motion, in meters?

2. Relevant equations
Angular frequency=sqrt(g/L)

3. The attempt at a solution
im trying to find the length of the pendulum from the graph provided but im not sure how to do that..
By looking at the graph i think the period is 6 seconds,and the amplitude is 1deg.. but im not sure how to proceed from here. Any advice would be helpful, Thanks!

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2. Oct 31, 2014

### Dr.D

Do you know the definiton of angular frequency? Do you know how frequency is related to the period? Do you know how to manipulate the frequency expression you gave to solve for L?

3. Nov 1, 2014

### quantumtimeleap

Yes, Dr. D is correct up there. Think what the definition of angular frequency is Warning: angular frequency is a bit different from frequency in Hertz you get from graphs as the number of full wavelengths per second.

You already know the relationship between angular frequency and length of the string. ($\omega = \sqrt{\frac{g}{l}}$)

Now you only have to determine angular frequency from the period that you determined from the graph. Good luck! ^^