Work/energy/kinematics rocket ship problem

[1barcafan]

Homework Statement

A rocket of initial mass of 2.85x10^6 kg is on the surface of the earth. if the initial acceleration is .20g, what is the required thrust? if the fuel is burned at a rate of 14,500 kg/s, with what speed is it ejected from the rocket?

Homework Equations

The Attempt at a Solution

The only thing i thought to do was convert the mass and acceleration of the rocket into Newtons. I also tried making the mass of the rocket into the rate of the fuel burning and tried to find how many seconds it would take to finish burning, but that was just a desperate attempt.

 

[Andrew Mason]

Homework Statement

A rocket of initial mass of 2.85x10^6 kg is on the surface of the earth. if the initial acceleration is .20g, what is the required thrust? if the fuel is burned at a rate of 14,500 kg/s, with what speed is it ejected from the rocket?

Homework Equations

The force accelerating the rocket (the rate of change of momentum of the rocket + gravity) is equal and opposite to the rate of change of of momentum of the ejected rocket gases.

\vec{F} = m_{rkt}a_{rkt} + m_{rkt}g = dp_{gas}/dt = v_{gas}dm_{gas}/dt

You are given all but v_gas.

AM