[填空题]
The tires of a car make 85 revolutions as the car redwjr-bk-nd;o/ 4-m q zauces its speed uniformly f j-*uy 2qh2 p;pryhyr1rom 90km/h to 60km/ 2*pju1r2r ypyhq;h y-h The tires have a diameter of 0.90 m. (a) What was the angular acceleration of each tire? $\approx$ $rad/s^2$(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