Question

A person pushing a wall hard is liable to fall back. Which law is related to this?
A. Newton’s first law
B. Newton’s second law
C. Newton’s third law
D. Newton’s gravitational law

Answer 1

Hint:Understand the given situation carefully. Look for the options, recall what each of the laws in the options states and try to relate it with the given situation. Check which law describes the situation and justifies why the person falls back.

Complete answer:
Given, a person pushing a wall hard is liable to fall back. We are asked to find which law is related to it. We check for options one by one, understanding which law states which condition.

Option A Newton’s first law: According to Newton’s first law, a body at rest tends to remain at rest or a body in motion tends to be in motion, unless and until any external force acts upon it. This law does not clarify why the person is liable to fall back, so option A is incorrect.

Option B Newton’s second law: According to Newton’s second law, the force acting on a body is equal to the product of mass and acceleration of the body. This law too does not clarify why the person is liable to fall back. So, option (B) is incorrect.

Option C Newton’s third law: According to Newton’s third law, to every action there is an equal and opposite reaction. Here, the person is applying force on the wall pushing the wall hard, since the wall is rigid and massive as compared to the person, there will be an equal amount of force in the opposite direction that is towards the person or there will be an opposite reaction to the person which will make him fall back. Therefore, option C justifies the situation. Thus, option C is correct.

Option D Newton’s gravitational law: This law is related to gravitational attraction between objects. Since, there is no gravitational force in the given situation. So, option D is incorrect.

Hence, the correct answer is option C Newton’s third law.

Note:Newton’s laws are the most important part of physics and this lead to the foundation of classical mechanics. It describes the motion of a body and when the body is acted upon by a force how the motion of the body will change. Do not get confused with which law states which condition, remember which law is related to which condition and try to relate it with the problem given.