Irodov Problem 1.180

This problem is a straightforward variation of 1.179 where v=wt and we have to determine at what rate the mass changes. One thing to note here is that the escape velocity of the gas u in this problem is not bold and is a scaler. This may be a bit confusing especially since in 1.178 and 1.179, he uses the bold vector notation. The essential idea in the notation is simply that when he uses vector notation, if the direction of ejection is in the opposite direction to that of the rocket, the corresponding scalar will only be negative in other words,




So now using the scalar u instead of the vector notation from 1.179 we have,