[填空题]
A stone is dropped from the rwp cw)rv8vb) xrc: ot6e3 *vn3oof of a building; 2.00 s afp-fq;7*7uv 8ruh (lxnl+wug oter that, a second stone is thrown straight down with an initial speedux-*l + pu o87fw;r(vnhqu7lg of 25.0 m/s and the two stones land at the same time.
(a) How long did it take the first stone to reach the ground? $t_1$ = s
(b) How high is the building? m
(c) What are the speeds of the two stones just before they hit the ground? #1 m/s #2 m/s