[填空题]
The tires of a car makxrsk;1kwop o -ne.9 eg,ew+- ze 85 revolutions as thimm2:t8t*7 1sx d9lrmwfs5li j//hyje 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 tire1sy2fx5mlst *w78tjri:m j/dlh9m/i? $\approx$ $rad/s^2$(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