[填空题]
The blades in a blendelpjah5i/u2ct: ad1 sw 5q-7uwr rotate at a j3x r1gwu8vx7rate of 6500 rpm. When the motor is turned off during operation, the bladeuwx8gjvrx 7 13s slow to rest in 3.0 s. What is the angular acceleration as the blades slow down? $rad/s^2$