Question

2. In a rocket, a large volume of gases produced by the combustion of fuel is allowed to escape through its tail nozzle in the downward direction with the tremendous speed and makes the rocket to move upward. Which principle is followed in this take off of the rocket? a) Moment of inertia b) Conservation of momentum c) Newton's first law of motion d) Newton's law of gravitation​

Answer 1

Newton's law of gravitation

Answer 2

Newton's third law of motion and principle of conservation of momentum

Explanation:

• Propulsion of rocket is based on the 'Newton's Third Law of Motion'.
• The combustion of fuel escapes through the tail in the downward direction. These gases (fuel) apply an equal and opposite reaction which is in accordance with the third law of motion by Newton.  
• This is the way rocket propulsion occurs.
• Another law used here is the principle of conservation of momentum which in this case applies to the momentum given to the rocket by the fuel (gases) which is equal and opposite to that of the gases. Total momentum is conserved during the entire process.