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Compound pendulum

by discombobulated
Tags: compound, pendulum
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discombobulated
#1
Apr23-07, 01:11 PM
P: 41
1. The problem statement, all variables and given/known data
I have calculated the value of the radius of gyration, k for a bar (and moment of inertia) and got three different values from three different methods. Now i need to determine which is the best value. I'm confused about how to do this, and how do i get the %uncertainty for k.

Value of k/m [Moment of Inertia / kgm2]
0.282 [8.93 x 10-3] (method 1)
0.289 [9.37 x 10-3] (method 2)
0.291 [9.49 x 10-3] (method 3)

(sorry i tried to separate this but for some reason it didn't work, so i used brackets to try and separate them)

Method 1 is from the intercept of the period squared x distance from centre of mass graph
Method 2 is from the dimensions of the bar
Method 3 from using the minimum time period


2. Relevant equations
T2D = 4/gπ2 D2 + 4/gπ2 k2 used in method 1

D = distance from centre of mass
T = radius of gyration
k = radius of gyrat
g= acceleration due to gravity

k = (1/12)(l2 + w2)1/2 used in method 2

k = (T2g)/ 8π2 used in method 3

3. The attempt at a solution

I don't think that the experimental value in method 1 is very accurate because of the problems in measuring the period, so would the best value of k be from method 2?
Is there a set value that k is meant to be for a compound pendulum consisting of a wooden bar pivoted at different holes?
I'm quite confused about this and would be really grateful for any help in understanding.
1. The problem statement, all variables and given/known data



2. Relevant equations



3. The attempt at a solution
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