 # Motion Class 9 CBSE Notes - Chapter 8

The world that we see around us is in constant motion – this is due to the fact that the earth itself is in motion, orbiting the sun at a speed of over 107,000 km/h. But exactly is motion and how do we define it?

## Describing Motion

If a body is constantly changing its position with respect to time or point of reference, then, that body is said to be in motion. There are various types of motion, namely:

1. Uniform Motion

It occurs when equal distances are covered in equal intervals of time by a body. Light travels in uniform motion through a vacuum.

1. Non-uniform motion

Unlike uniform motion, a body travels unequal distances in equal intervals of time. A car moving through traffic constitutes non-uniform motion.

1. Periodic motion

This is essentially a type of motion that repeats itself at periodic intervals of time. A vibrating tuning fork is an example of periodic motion

1. Oscillatory motion

This is a form of periodic motion that occurs in a regular cycle. A sine wave, the swing of a pendulum are examples of oscillatory motion.

Motion class 9 also explains the concept of motion along a straight line, one of the most simple types of motion. It is also called linear motion or rectilinear motion.

## Motion Class 9 Notes – Questions

1. What do you understand by the term “motion?”
2. Explain Uniform Motion
3. What is the difference between Uniform and Non-Uniform Motion?
4. What is meant by the rate of change of velocity?
5. Give 3 examples of circular motion.

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