# NCERT Solutions for Class 9 Science Chapter 9 Force and Laws of Motion

NCERT Solutions for Class 9 Science Chapter 9 Force and Laws of Motion: What causes a body to move? How we can stop a moving body? How we can change the direction of a body? The answer to all the three questions is by applying a force. In NCERT Solutions for Class 9 Science Chapter 9, we study about force and Newton's laws of motion. The chapter is very important as far as your higher studies in science are considered. Another main topic of NCERT Solutions for Class 9 Science is inertia. There are many interesting real-life situations related to NCERT Solutions for Class 9. We will see a few of them

One of the important topics of NCERT Solutions is Newton's Laws of Motion

i) Newton's first law of motion:

Everybody continues its state of uniform motion along a straight line or state of rest unless acted by an external force. For example, if we hit a resting ball it will move and will not stop unless there is an external force. The external force acting here is friction which opposes the motion of the ball.

ii) Momentum

The momentum of a body is the product of its mass and velocity.

Newton's second law of motion: The rate of change of momentum of a body is directly proportional to the unbalanced force applied in the direction of the force.

If a body of mass m is moving with initial velocity u along a straight line. It is uniformly accelerated to a velocity v by applying a force for time t then, the rate of change of momentum = force applied. That is force applied

$F=\frac{m(v-u)}{t}$

iii) Newton's third law of motion

Newton's third law of motion states that every force has equal and opposite reactions. For example, when a bullet is fired from a gun, the gun exerts a forward force on the bullet and the bullet exerts a backward force on the gun. That is why the gun moves back (recoil of the gun) when fired.

Another important topic of NCERT Solutions for Class 9 Science Chapter 9  is Inertia

The inertial of an object is its natural tendency to continue its state of rest or motion. Mass is the measure of inertia of an object. For example, when a moving bus applies brake  people in the bus moves forward, this is due to the inertia of motion

The main topics of NCERT Solutions for Class 9 Science Chapter 9 Force and Laws of Motion are:

9.1 Balanced and Unbalanced Forces

9.2 First Law of Motion

9.3 Inertia and Mass

9.4 Second Law of Motion

9.5 Third Law of Motion

9.6 Conservation of Momentum

## NCERT Solutions for Class 9 Science- Chapter Wise

 Chapter No. Chapter Name Chapter 1 Matter in Our Surroundings Chapter 2 Is Matter Around Us Pure Chapter 3 Atoms and Molecules Chapter 4 Structure of The Atom Chapter 5 The Fundamental Unit of Life Chapter 6 Tissues Chapter 7 Diversity in Living Organisms Chapter 8 Motion Chapter 10 Gravitation Chapter 11 Work and Energy Chapter 12 Sound Chapter 13 Why Do We Fall ill? Chapter 14 Natural Resources Chapter 15 Improvement in Food Resources