[填空题]
A stone is dropped from the roof of a high build;+qqgf vy 2 ))xfu2xwring. A second stone is dmea- i8akuih1 . u9j1pzbtq9a.t:nx 1ropped 1.50 s later. How far apart are the stone.i8uzatmj.i- a:b1xeh9tuqp 9a 1 k1ns when the second one has reached a speed of 12.0 m/s ? m