Concepts

Class 9
Chapter 8 Class 9 - Motion

To learn about motion, we first learn what are stationary bodies and moving bodies

Stationary Bodies

Bodies which do not change their position with time are called stationary bodies

In easy language,those bodies which are fixed at one place and do not move are stationary bodies

Example

A tree is stationary(as it does not move)

A house is stationary (as it does not move)

Moving Bodies

Bodies whose position keep on changing are called moving bodies

In easy language,those bodies which are not fixed at one place and keep on moving are called moving objects

Example

A bird flies from a tree

### When is a body set to be in motion?

A body is said to be in motion when its position keeps on changing,taking a stationary object as reference.

Example

Here Road is Stationary but Car is in Motion as position of car is changing with respect to road

Example

A bird flies from a tree

Here, the tree is stationary but bird is in motion as the position of bird is changing with respect to the tree.

### Types of Motion

There are many different types of motion. Some common types are

• Linear Motion
• Rotational Motion
• Oscillatory Motion
• Vibration

In this chapter, we only talk about Linear Motion - Motion in a straight line

Note

Sometimes Movement is not visible to Naked Eye

If Movement is fast,we can easily observe it with naked eye

But if movement is slow,its movement cannot be observed easily

Example

it is easier to observe motion of 'seconds hand' of clock

But movement of Hour Hand Cannot be observed easily because movement is slow