- #1
student34
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Homework Statement
You hang a thin hoop with radius R over a nail at the rim of the hoop. You displace it to the side (within the plane of the hoop) through an angle β from its equilibrium position and let it go. What is its angular position when it returns to its equilibrium position (use the gravitational potential energy equation).
Homework Equations
K(1) + U(1) = K(2) + U(2)
U(1) = mgh
h = R - Rcosβ
K(2) = (1/2)mv^2 = (1/2)m(ω^2)R^2
The Attempt at a Solution
0 + U(1) = K(2) + 0
mgh = (1/2)m(ω^2)R^2
mg(R - Rcosβ) = (1/2)m(ω^2)R^2
ω = √((2g(1 - cosβ)/R)
The answer in my textbook is exactly the same as my answer but without the 2. What could have happened to the 2?