[填空题]
The blades in a blender rotate at a rate2ukg (lry f c*x05cb3u of 60 j9ckwx0(9r2rlegyi 500 rpm. When the motor is turned off during operation, the blades s gk9e 0y(lcjrwi20rx9low to rest in 3.0 s. What is the angular acceleration as the blades slow down? $rad/s^2$