[填空题]
The blades in a blende*5 buyp :uy1p9sffvb/r rotate at a rate of 6500 rpm. When the motor is tutnkpody /7eht ,51sxa 4ptc :pazb//9rned off during operation, the blades slow to rest in 3.0 s. What is the angular acceleration as the blade9xezp/a n d 5ho4p7tc :,/t bkpsa/1tys slow down? $rad/s^2$