[填空题]
Starting from rest in the pit area, a racewd yj(f ,( .,iljuf/izgg h:s7 car accelerates at a u9fkg+5;br 3 rx6fxn1nsj 8xs(rgkk) yniform rate to a speed of 45 m/s in 15 s, moving on a circular track of radius 500 m. 5r6 ;138jf)f(xxrn bs g+ g kykn9srxk(only fill in numerical value in the blanks)
(a) Calculate the tangential acceleration. $m/s^2$
(b) Calculate the radial acceleration when the instantaneous speed is equal to 30 m/s. $m/s^2$
