1. The problem statement, all variables and given/known data The balance wheel of a watch is a thin ring of radius 0.95 cm and oscillates with a frequency of 3.10 Hz. If a torque of 1.1x10-5 Nm causes the wheel to rotate 45°, calculate the mass of the balance wheel. 2. Relevant equations I=mr2 T=(2π)sqrt(I/mgh) τ=-Kθ 3. The attempt at a solution I got an answer but it's wrong... Here's the work I did: 1.1e-5=-K(pi/2) K=-7.003e-6 19.5 rad/s = sqrt (7.003e-6/(M(0.0095m)2)) 380.25 rad/s2 = 7.003e-6 Nm / 9.025e-5m M M*0.0343 m/s2 = 7.003e-6 Nm m = 2.04e-4 kg The answer should be 0.41g (I realized just now that I took the square root of a negative number earlier. I tried to redo the problem but I'm still stuck...) Thanks!