[填空题]
A rocket of total mass 3180 kg is tra is l;bj/u/s .,4reihp/bqbc) veling p :o06g f. bym(gz*chhin outer space with a velocity of 115m/s To alter its course by 35. hgoc:zg0h*m b.(f6py0 $^{\circ} $, its rockets can be fired briefly in a direction perpendicular to its original motion. If the rocket gases are expelled at a speed of 1750m/s how much mass must be expelled? kg
