[SOLVED] Grindstone angular acceleration 1. The problem statement, all variables and given/known data Object: a disk-shaped grindstone of mass 1.69 kg and radius 7.95 cm that operates at 707 rev/min. When the power is shut off, you time the grindstone and find it takes 32.1 s for it to stop rotating. What is the angular acceleration of the grindstone? (Assume constant angular acceleration.) 2. Relevant equations W=.5mv^2 V=distance/t W=Wo+at a=alpha, which is angular acceleration 3. The attempt at a solution V=[707*(2pi/60)]/32.1 = 2.31m/s W=0 Wo=.5(1.69)(4.50^2) = 4.50J 0=4.50+a(32.1) therefore, a=-.140 rad/s^2 however, this is the wrong answer according to the program. It didn't have a problem with the units though, so I don't know what I am doing wrong. Please point out any wrong assumptions or completely wrong or silly mistakes. THANK YOU!