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The initial mass of a rocket is 1000 kg. Calculate at what rate the fuel should be burnt so that the rocket is given an acceleration of 20 m s⁻². The gases come out at a relative speed of 500 m s⁻¹ with respect to the rocket: [Use g = 10 m/s²]

1. 6.0 × 10² kgs⁻¹
2. 500 kg s⁻¹
3. 10 kg s⁻¹
4. 60 kg s⁻¹

Correct answer: 60 kg s⁻¹

Solution

The correct option is right because it applies the rocket equation, which relates thrust, mass flow rate, and exhaust velocity. To achieve the desired acceleration, the mass flow rate of the fuel must be 60 kg/s, ensuring that the thrust produced is sufficient to overcome both the gravitational force and provide the necessary upward acceleration.

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