00:01
Okay, so we're doing chapter 9 problem 83 here.
00:04
So it says a rocket is traveling 1850 meters per second away from earth at an altitude of 6 ,400 kilometers fires its rockets, which eject a speed 1 ,300 meters per second relative to the rocket.
00:27
If the mass of the rocket at this moment is, so mass at the moment is, so mass at.
00:34
That t equals 0 equals 2 ,500 kilograms and an acceleration of 1 .5 meters per per second it desired what rate must cast be ejected.
00:49
Okay, well this is a lot of information but we're going to use equation 119 .9 .19 that's what i'm looking for.
00:57
That tells us the mass times the acceleration here.
01:02
Is given by the external force plus the relative velocity at the rate of mass ejected.
01:13
Okay.
01:16
So we can rearrange this for what the m d t is, and this becomes one over the relative velocity, times the total mass dvd t, minus the external force.
01:36
Okay...