Class 9 Science chapter 8, Motion, introduces students to the concept of motion and its various forms. The chapter covers topics such as distance and displacement, speed and velocity, acceleration, and laws of motion. It also covers the application of these concepts in real-world scenarios. Such as the motion of objects under the influence of forces and the motion of projectiles. The chapter Aims to help the students to understand the fundamental principles of motion and how they can be applied to explain the behavior of objects in the world around them.

In class 9 science chapter – 8 Motion the students are going to understand the following topics:-

## Motion

Motion is the change in position of an object with respect to its surroundings in a given period of time. A body is in motion if it changes its position continuously with reference to the point. Objects can be in motion relative to a reference point or frame of reference. For example, a car moving along a road would be in motion relative to the road, while a person riding in the car would be in motion relative to the car. Motion can be of different types depending upon the type of path by which the object is going through.

### Scalar and Vector Quantity

A scalar quantity is a physical quantity that is described by a single value, such as distance, time, or mass. Scalar quantities do not have any direction associated with them. For example, distance is a scalar quantity because it is simply a measure of how far apart two points are, regardless of the direction of the distance.

On the other hand, a vector quantity is a physical quantity that is described by both a value and a direction. Examples of vector quantities include velocity, acceleration, and force. These quantities have a magnitude and a direction. For example, velocity is a vector quantity because it is described by both the speed of an object and the direction it is moving in.

### Distance and Displacement

- The actual path or length travelled a object during its journey from initial position to final position is called its Distance.
- Distance is a scalar quantity.

Displacement is a vector quantity that represents the change in position of an object. It is defined as the distance and direction between the initial and final position of an object. It is a measure of how far an object has moved from its starting point, regardless of the path taken. The displacement vector points from the initial position to the final position of an object. For example, if a car moves from point A to point B, its displacement is the vector pointing from point A to point B.

### Uniform Motion

Uniform motion is a type of motion in which an object moves at a constant speed in a straight line. In other words, the velocity of an object in uniform motion is constant and does not change over time. If an object is in uniform motion, the distance traveled and the time taken to travel that distance are directly proportional. This means that the object covers equal distances in equal intervals of time.

In contrast, non-uniform motion is a type of motion in which an object’s speed changes over time. This can happen when an object is accelerating (speeding up) or decelerating (slowing down).

### Non-Uniform Motion

Non-uniform motion is a type of motion in which an object’s velocity changes over time. This means that the speed of the object is not constant and can either be increasing or decreasing. It can be further classified into two types of non-uniform motion: acceleration and deceleration.

Acceleration is a change in velocity, where an object’s speed is increasing over time. This can be caused by a net force acting on the object or by a change in the direction of its velocity. For example, a car accelerating from a stop sign is in non-uniform motion.

Deceleration is the opposite of acceleration, it is a change in velocity where an object’s speed is decreasing over time. This can be caused by a net force acting on the object in the opposite direction. For example, a car slowing down to a stop is in non-uniform motion.

In non-uniform motion, the distance traveled and the time taken to travel that distance are not directly proportional, unlike uniform motion.

After reading this chapter you can go through the next chapter of class 9 Science. Link is given below :-