A 740 gram grinding wheel 21.5 cm in diameter is in the shape of a uniform solid disk. (We can ignore the small hole at the center.) When it is in use, it turns at a constant 240 about an axle perpendicular to its face through its center. When the power switch is turned off, you observe that the wheel stops in 45.5 s with constant angular acceleration due to friction at the axle. What torque does friction exert while the wheel is slowing down?