A(n) 4100 kg rocket traveling at 2500 m/s is moving freely through space on a journey to the moon. The ground controllers find that the rocket has drifted off course and that it must change direction by 9.5? if it is to hit the moon. By radio control the rocket's engines are fired instantaneously (i.e., as a single pel- let) in a direction perpendicular to that of the rocket's motion. The gases are expelled (i.e., the pellet) at a speed of 3900 m/s (relative to the rocket).
What mass of gas must be expelled to make the needed course correction?