1. The problem statement, all variables and given/known data A phonograph turntable with an initial angular velocity of 78 rpm continues turning for 40 rotations after being switched off. What is the angular deceleration of the turntable? Assume constant angular deceleration. 2. Relevant equations [itex]\alpha[/itex]=([itex]\omega[/itex]-[itex]\omega[/itex]0)/t θ-θ0=1/2([itex]\omega[/itex]0+[itex]\omega[/itex])t 3. The attempt at a solution t = (40 rot - 0 rot) / 1/2(78 rpm + 0 rpm) = 40/39 min [itex]\alpha[/itex] = (0 rpm - 78 rpm) / (40/39 min) = -76.05 rpm2 The answer needs to be in rad/s2 (-76.05 rpm2)(2∏ rad/rot)(min2/s2)=-7.96 rad/s2 The back of the book tells me this answer is incorrect. I would appreciate any insight into the error(s) I am making. Thank you!