Question

A rocket works on which law of motion?
A) Newton’ First law
B) Newton’s Second law
C) Newton’s Third law
D) None of these

Answer 1

Hint: - The rocket is pushed from ground by expelling gases at very high velocity.This is called action and when the rocket is pushed forward from the ground. This is called reaction. When these both are added they give the sum as zero.

Complete Step by Step Solution: -
There are three laws of motion which were proposed by Sir Isaac Newton. They are-
Newton’s first law of motion: The Newton’s First law states that, “a body is said to be at rest it will remain at rest and if a body is at motion it will remain in motion until and unless an external force is applied on it”.
Newton’s second law of motion: The Newton’s second law states that, “when a force acts on an object it is equal to the product of mass of object and acceleration”. Mathematically, it can be represented as-
$F = ma$
where, $m$ is the mass of an object and $a$ is the acceleration of an object.
Newtons’ third law of motion: Newton's third law states that, “for every action there is an equal and opposite reaction”.
According to the question, when a rocket uses gases to escape from the ground at a very high velocity. We can say this as action. Due to this action of gases, the rocket is pushed forward by gases because of the principle of conservation of momentum. This is called reaction. Hence, there is an equal and opposite reaction.

So, Newton’s third law works on the rocket.

Note: - The net force acting on a body in Newton’s third law is zero. It can be represented mathematically as-
Let ${F_{AB}}$ be the force which exerts the force from body A to B and ${F_{BA}}$ be the force which exerts force from body B to A.
$\therefore {F_{AB}} = - {F_{BA}}$
The net force acting on the body is-
${F_{net}} = 0$