AP Power in Rotation

Problem 3 in the Rotational Energy WS asked you to find power using torque x omega at 15 and 30 seconds. Try finding the power from the rate of change of rotational KE , i.e. the rate of change of I omega^/2.

To do this remember I is constant so we have I/2 (omegaf^2- omegai^2)/delta t. Approximate omegaf as omegai + alpha delta t. Carry out the (omegai + alpha delta t)^2. Then cancel terms where appropriate and divide the numerator through by delta t . Then let delta t get infinitesimally small so any term with a delta t goes to zero. Use omega at 15 and see if the power matches the one found from torque x omega.