Question

Rocket works on the principle of conservation of:
(a). Mass
(b). Energy
(c). Momentum
(d). Velocity

Answer 1

- Hint: A range signifies a collection or a set of similar things, in this case, we are taking frequency as a range, there will be a higher frequency and a lower frequency associated with the range. Recoil of a gun is a good example to understand rocket propulsion. It depends upon the conservation laws. As we know, the rockets will remove or burn their parts at particular intervals to maintain the momentum i.e. it is reducing the mass of the rocket and increasing their velocity.

Complete step-by-step solution -

To understand the science behind the Rocket, you can take an example of a gunshot. Shooting a gun also demonstrates the application of conservation of momentum. As we pull the trigger, the bullet comes out at a very high speed, but we also observe a recoil of the gun. This happens to conserve momentum. The momentum gained by the bullet is equal to and also the reason for the recoil of the gun.
Same as this, the gases inside a rocket are made to propel out of the Rocket at a very high speed. This, in turn, gives a push to the rocket in the opposite direction to conserve the momentum. Thus a lot of fuel needs to be burned to provide the rocket a sufficient amount of force to escape the earth's atmosphere.
The correct option is c. That is, the rocket works on the law of conservation of momentum.

Additional information:
Let's understand it mathematically also. Let us suppose a rocket has a mass $M_0$ initially when all the fuel is present at time t. After its launch, let's think its mass reduces to \[{{M}_{f}}\] at time \[t+dt\]. We can say that the thrust force with which the rocket accelerates depends upon the mass flow rate \[\dfrac{dm}{dt}\], the velocity of exhaust \[{{v}_{e}}\], and the force due to pressure difference at the nozzle of Rocket \[({{P}_{0}}-{{P}_{e}})\]. \[{{A}_{e}}\] is the area of a nozzle through gas exits.
 $F={ v }_{ e }\dfrac { dm }{ dt } +({ P }_{ e }-{ P }_{ 0 }){ A }_{ e }$

Note: For a rocket mass of the system will not be a constant, since the rocket ejects fuel to provide thrust. To maintain the momentum velocity also changes. So both quantities are not conserved. Rocket obeys the law of conservation of energy also. In this case, the chemical energy .i.e. fuel stored in the rocket converted into work and heat energy during the traveling. Conservation of momentum is only necessary to describe the rocket working principle. Conservation of energy is inbuilt in every system.