find the initial upthrust on the rocket

Question

a rocket has a mass of top hundred kg and 90% of is fuel. It ejects fuel vapour at the rate of 1 kg per second with a velocity of 500 m per second relative to the rocket .It is suppose that a rocket is outside the gravitational field .The initial of thrust on the rocket when it is just start moving upward is

Answer 1

T = thrust

 

m_dot = rate at which fuel is expended = 1 kg/s

 

u_e = exit speed of expended fuel = 500 m/s

 

T = m_dotu_e = (1 kg/s)(500 m/s) = 500 kg·m/s² = 500 N