[填空题]
(a) If a volcano spews a 500-kg rock verticc8ljg/pyaqg2c5j5 ayv4 b44mal*om(1t q ,trt )zx9gmdly upward a distance of 500 m, what wa( g tro)t9*zt,xdmmq1 s its velocity when it left the volcano? $\approx$ m/s
(b) If the volcano spews the equivalent of 1000 rocks of this size every minute, what is its power output? $\approx$ $a\times10^b$ W a = b =