- #1

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## Homework Statement

## Homework Equations

PE spring = .5 kx^2

KE rotation = .5 I w^2

## The Attempt at a Solution

I tried to do a conservation of energy

(Note: I = moment of inertia, L = length)

3*.5*k L^2 = .5 I w^2

I =3 M R^2 ---> a^2 = b^2 + c^2 -2bc cos(a) (the reason why I am using law of cosines is to find the radius from the center to each point mass)

R = L / sqrt(3)

I = ML^2

3*.5*k*L^2 = .5*M*L^2 *w^2

k = 1/3 * Mw^2 which is wrong. The answer is C. How do you do this?