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GATE 2024 AE – Question 57

Propulsion · Rockets: thrust equation, specific impulse, multi-staging, solid and liquid propellant rockets · 2 marks · Numerical answer

A chemical rocket with an ideally expanded flow through the nozzle produces $5 \times 10^6$ N thrust at sea level. The specific impulse of the rocket is 200 s and acceleration due to gravity at the sea level is 9.8 m/s$^2$. The propellent mass flow rate out of the rocket nozzle is _________ kg/s (rounded off to the nearest integer).

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Correct answer: 2551

Explanation

The thrust is $F = \dot m I_{sp}g_0$, so $\dot m = \frac{5 \times 10^6}{200 \times 9.8} = 2551$ kg/s.