[填空题]
The tires of a car make 85 o e rg;i+o7,fj,x9ekv revolutions as the 61 2uci a1dnpz 2gaje+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 ad1+n g2jua2 e cz16pitire? $\approx$ $rad/s^2$(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