Question

Rocket works on the principle of conservation of
1. Angular momentum
2. Energy
3. Mass
4. Linear momentum

Answer 1

Correct Answer - Option 4 : Linear momentum

CONCEPT:

• Momentum: The product of mass and velocity is called the momentum of the body.

Momentum (P) = m × V

Where m = mass of the body, V = velocity of the body.

• Conservation of momentum: Whenever there is no net external force on the system then the total momentum of the system remains constant.

Initial momentum (P1) = Final momentum (P2)

i.e., \({m_1}{v_1} = {m_2}{v_2}\)

here, mass of two object = m1 & m2, velocity of two object = v1 & v₂

• Angular momentum: It is defined as the property of any rotating object given by moment of inertia times angular velocity.
  • ​It is the property of a rotating body given by the product of the moment of inertia and the angular velocity of the rotating object.
  • It is a vector quantity, which implies that here along with magnitude, the direction is also considered.

EXPLANATION:

• In a rocket, gasses at high temperatures and pressure are created by the combustion of fuel.
• They escape with a high constant velocity via a nozzle.
• The large, backward momentum of the gasses gives the rocket an equal forward momentum.
• However, due to the decrease in the mass of the rocket fuel system, the acceleration of the rocket continues to increase.
• Thus a rocket works on the principle of conservation of Momentum. 
• Since the energy of the rocket's fuel converts into heat energy that propels the rocket. So the energy of the rocket only is not conserved. The energy of the rocket and the surrounding will be conserved but not of the rocket.
• Similarly, the mass of the rocket decreases as the fuel burns. So mass is not conserved.
• There is no rotation in the rocket so no meaning of spin angular momentum here.

So the Rocket works on the principle of conservation of linear momentum.