1. The problem statement, all variables and given/known data How to derive W=(.5*I)*((ωf^2)-(ωi^2)) from W=τ*(θ) 2. Relevant equations The two equations seen above (big W is work; little w is rotational velocity, τ is torque, alpha=rotational acceleration). s=r*θ a=r*(alpha) (ωf^2)-(ωo^2)=2*(alpha)*(θ) F=r*τ F=ma 3. The attempt at a solution W=T*(θ)=(F/r)*(s/r)=(r^-2)*F*s=(r^-2)*ma*s=(r^-2)*m*(r*alpha)((ωf^2)/(2*alpha))*r =0.5*m*ωf^2 Obviously this isn't right. What went wrong?