JEE Main Physics question
A rocket standing vertically on a launch pad has to start moving up with practically zero initial velocity. If the initial mass of the rocket is 5×10⁵ kg, then the rate of burning of the fuel should be (take g = 10 ms⁻² and velocity of exhaust gases = 10 kms⁻¹)
Answer: (C)
Solution
At liftoff, thrust just equals weight: (dm/dt)· = Mg ⟹ dm/dt = Mg/ = (5×10⁵×10)/10⁴ = 500 kgs⁻¹.