A rocket ascends from rest in a uniform gravitational field by ejecting exhaust with constant speed u.(adsbygoogle = window.adsbygoogle || []).push({});

Assume that the rate at which mass is expelled is given by dm/dt=ms, where m is is the instantaneous mass of the rocket and s is a cosntant, and that the rocket is retarded by air resistance with a force bv where b is a constant. find the velocity of the rocket as a function of time.

in my text they have proven the case when the total external force is F and it equals: F=mdv/dt+udm/dt, i used this in the calculation, and got:

mg-bv=mdv/dt+udm/dt, but i dont think this correct, your help as always is appreciated.

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# Homework Help: A Rocket question (momentum).

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