NCERT Solutions for Class 11 Physics, Chapter 5 - Laws of Motion

In this chapter, you will learn about the laws of motion. This is one of the most important topics as these laws are used repeatedly in other topics as well. You will study the motion of a body taking into consideration the main cause behind the motion i.e. Force. Chapter 5 of the book, Physics Part-I, consists of the 11 sub-sections, where each section explains the various aspects of the chapter in details. Here is the list of subtopics that fall under this chapter.

Let us take a look at the subtopics of Class 11 Physics, Chapter 5, Laws of Motion. 

5.1 Introduction

5.2 Aristotle’s fallacy

5.3 The law of inertia

5.4 Newton’s first law of motion

5.5 Newton’s second law of motion

5.6 Newton’s third law of motion

5.7 Conservation of momentum

5.8 Equilibrium of a particle

5.9 Common forces in mechanics

5.10 Circular motion

5.11 Solving problems in mechanics

In class 11 Physics, Chapter 5, you will learn:

Section 5.1: In this section, you will learn that for a body to be in uniform motion, velocity is required. But, for a body to be in non-uniform motion, acceleration is also needed. You will also study the fact that in order to be in motion, an external force is required to be exerted upon the body. For example, upon pushing a ball, it moves — similarly, the branches of a tree swing when the wind blows.

Section 5.2: In this section, you will learn that an external force is required in order to keep a body in motion. However, there is a major flaw in his statement. In the real world, a constant force is required in order to keep a body in motion because of a lot of external factors such as friction. In order to compensate for the loss due to friction, a constant external force is required.

Section 5.3: In this section, it is explained that inertia is the property of a body, which prevents it from ”changing” its state of rest or motion. If the net external force applied on a body is zero, then the body continues to stay in the state of rest or uniform motion, unless acted upon by external forces.

Section 5.4: In this section, you will learn Newton’s first law of motion, that every object tends to stay in its state of rest or constant motion, until and unless acted upon by some external forces.

Section 5.5: In this section, you will learn about Newton’s second law states that the acceleration of a body is directly proportional to the external force applied on the object and inversely proportional to the mass of the object.

Section 5.6: In this section, you will get to know about Newton’s third law that states that every action has an equal and opposite reaction. For example, if you are punching a door, you will feel a similar amount of force on your fist- as much force as you are applying while punching the door.

Section 5.7: In this section, the explanation for the second and third law of motion leads to the law of conservation of momentum. It states that in an isolated system, mutual forces between pairs of particles in the system can cause momentum change in individual particles, but since the mutual forces for each pair are equal and opposite, the momentum changes cancel in pairs, and the total momentum remains unchanged.

Section 5.8: In this section, you will get to know about that the external force on a particle is zero, the particle is said to be in equilibrium. For more information, you may refer to the Laws of Motion Class 11 Questions with Solutions Pdf here at UrbanPro.

Section 5.9: In this section, you will get to understand that under mechanics, a lot of different kinds of forces are seen. One of the most common forces that exist is the gravitational force. Some other common types of forces are spring force or string force. These are contact forces, as they need to have contact with the body in order to apply the force.

Section 5.10: In this section, you will learn that for a body moving in a circular motion, its force is directed towards the centre of the circle. This force is known as the centripetal force.

Section 5.11:  In this section, you will understand upon learning the three laws of motion, problems related to them can be solved easily.

For a better understanding of this chapter, refer to NCERT Solutions for Class 11 Physics Chapter 5 Pdf here at UrbanPro.