[填空题]
A world-class sprintezx6s*nid, h 3wr ch(1iz3cz-w ordu1ls4ys rgy*ye,4 1wan burst out of the blocks to essentially top speed (of about 11.5 m/s) in the first 15.0 m of the race. What is the average acceleration of this sprinte1zi 3yy14,czr( 1yue gs sro*h-wdlw4 r, and how long does it take her to reach that speed? $\approx$ = $m/s^2$ (retain two decimal places) s
