1. The problem statement, all variables and given/known data A 1.5 hp motor drives a machine disk having a mass of 4.5 kg and a diameter of .4 m from rest to a speed of 750 rpm. How long does it take to reach the operating speed? 2. Relevant equations angular momentum torque 3. The attempt at a solution I'm not really sure where to start with this problem. I don't know how to find time without distance or acceleration. I tried solving for acceleration but I'm not sure how horsepower relates to torque.