[填空题]
The tires of a car make 85 revolutions as the car reduces its mqlvck y: b buwybz5yf7a.+9cp89)g6speed uniforml yl-287 h ifpoa7cetv *z,mk1ty from 90km/h to 60km/h The ti17pm*a,hlezif -tc 7tov2 yk8res 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