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## Homework Statement

A clock balance wheel has a period of oscillation of 0.250 s. The wheel is constructed so that its mass of 10.0 g is concentrated around a rim of radius 0.600 cm.

a) What is the wheels moment of inertia? kg m^2

b) What is the torsion constant of the attached spring? N m / rad

## Homework Equations

I=mr^2[/B]

## The Attempt at a Solution

starting with part a)

I have gone mr^2 and gotten 3.6x10^-7 so i assumed that answer didnt make sense, I thought it could be because it says the mass is concentrated around the rim so do i treat that as if it was a ring?

If so I know that dI = dm r^2

so ∫dI = r^2 ⋅ ∫dm

so I = r^2 M

where M is the mass of the whole ring system.

Am I correct in this working or was my first calculation correct ?

[/B]