1. The problem statement, all variables and given/known data A flywheel in the form of a uniform disk (I = ½ MR2) 5.0 ft in diameter, weighs 650 lb. What will be its angular acceleration if a net force of 225 ft-lb acts it upon? If the disk is rotating at 1200 rev/min, what torque is required to stop it in 30 minutes? 2. Relevant equations T=I[itex]\alpha[/itex]=Fr 3. The attempt at a solution I need help in the first question, because apparently I arrive with a different answer from the solution that my teacher gave me. I just wanted to know if I got it wrong or my teacher forgot something So using the definition of torque, I solve for alpha which is alpha = FR/I Defining I in the equation gives alpha = FR/(1/2)MR2 Since the given is weight, I still have to define mass in the equation alpha = FR/(1/2)(W/g)R2 Substituting the values, I'll have alpha = (225)(2.5)/(1/2)(650/9.8)(2.5)2 alpha = 2.71 rad/s2 The solution in my note was alpha = 2g(Torque)/WR2 which results to 3.54rad/s2 Am I missing something? Or is everything just right?