HELP!!!! im sooo confused?? (1 Viewer)

[ixsamanthaxi]

An apollo launch vechicle has a total mass of 3.4x10^6kg at lift off. The first stage contains 2.0x10^6kg of propellants (fuel and oxygen) which is consumed at a rate of 1.4x10^4kg s

a) find the minimum thrust of the engines at lift off

b) if that thrust (from a ) is sustained, find the time over which the first stage operates and the acceleration of the vehicle at that time. (neglect air friction, but assume the whole whole flight is vertical)

c) find the speed of the exhaust gases. (recall that force can be equated to the rate of change in momentum)

thanks to anyone who atempts ANY of my questions your replies would be greatly appreciated.

 

[k02033]

http://community.boredofstudies.org/263/space/206253/help-thrust-question.html

here was our pretty poor attempt at it..
i think the last equation by 3unit was the only one thats even remotely correct

 

[ixsamanthaxi]

hey thanks heaps everything is much clearer now