For a Rocket propulsion velocity of exhaust gases relative to rocket is 2 km/*. If mass of rocket system is 1000 kg, then the rate of fuel consumption for a rocket to rise up with acceleration 4.9 m/s2 will be :
(1) 12.25 kg/*
(2) 17.5 kg/*
(3) 7.35 kg/*
(4) 5.2 kg/*
Correct Answer is: (3) 7.35 kg/s
Here v dm/dt = m(4.9 + 9.8) = (14.7)m
v = 2km/* m = 1000
2000 dm/dt = 14.7 × 1000
dm/dt = 14.7/2 = 7.35 kg/*
