Question

Q.17. A 1000 kg rocket is fired from earth so the exhaust speed is 1000 m/s. Then the mass of fuel burning per second, to provide initial thrust to overcome its weight is (g = 10 m/$s^2$)
(1) 5 kg
(2) 15 kg
(3) 10 kg
(4) 2.5 kg

Answer 1

DEar student
$$\begin{gathered} thrustforce{F}_t=v_{rel}dm/dt \\ herethrustforceneeded=massofrocket*g=1000g \\ herevrel=1000m/s \\ so \\ 1000g=1000dm/dt \\ dm/dt=10kg/sanswer \end{gathered}$$