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Momentum09
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Homework Statement
A small metallic bob is suspended from the ceiling by a thread of negligible mass. The ball is then set in motion in a horizontal circle so that the thread describes a cone.
Given: Length of string = 2.8m
Angle between string and vertical: 21 degrees
Mass of bob: 2.9kg
Homework Equations
I = mr^2
w = square root of [g/(lcos(theta)]
Momentum = I x w
The Attempt at a Solution
I first calculated the angular velocity by plugging numerical values into the equation and got 1.936 rad/s. Then, I found out the moment of inertia of the bob by multiplying 2.9 x 2.8^2 [this is the step I'm not sure of], but the answer wasn't right. Is there something I missed out?
Thank you for your help!