[填空题]
The tires of a car make 85basww d4-c s s(sn /bzpl*(0)q r y/ n8ebr2uop8evolutions as the car reduces its speed uniformly from 90km/h to 60km/h The tires have a diameter of 0.90 m. (a) What was the angular acceleration of each tire?o p8yn82r/be u $\approx$ $rad/s^2$(round to two decimal place) (b) If the car continues to decelerate at this rate, how much more time is required for it to stop? s