the useful carry of a racket is as 5% of all its mass,the other part is fuel.if the racket start moving from the static state, without the effect of F(est) [esternal forces] how is the finalize velocity if the velocity Usc is 5 km/s
I will assume that "useful carry" means "payload"; that "racket" means "rocket"; that "esternal" means "external"; that "physic" means "physics"; that "finalize" means "final", and that "Usc" is the velocity of the exhaust gases with respect to the rocket. I am curious about what the 'sc' stand for.
If these assumptions are correct, then the final rocket velocity is
Vf = Usc ln (Mi/Mf) = Usc*ln20
Mi is the initial rocket Mass and Mf is the final rocket mass