The initial mass of a rocket is 30 tons, the initial acceleration is 3g. The rocket has four nozzles each of 20 cm diameter. The remaining data are the same as in the previous problem. Find the initial fuel consumption (together with the oxidant), the density and the pressure of the gas ejected from the nozzle. 

Answer

588 kg/s ; 2.34 `kg//m^3 ; 3.86 xx10^5 Pa = 3.8 atm`

Explanation

The thrust may be found from Newton.s second law: `F - mg = ma`, whence `F = 4mg`. The consumption of fuel together with the oxidant is `mu = F//u = 4 mg//u`
The density of the gas is found from the continuity equation:
`rho = mu/(Su) = (16 mg)/(pi D^2 u^2)`
The pressure is found from the Mendeleev-Clapeyron equation.