# Motion

When an object changes its position with elapse of time in respect to a stationary object, such as a building, electric pole, etc., the object is said to be in motion.

**Slow and Fast Motion:** If an object **A** covers a distance in less time and another object **B** covers the same distance in more time, the object **A** is called a faster moving object and object **B** is called a slower moving object. In other words, object **A** has faster motion and object **B** has slower motion.

## Types of Motion

### Rectilinear Motion

Motion along a straight line is known as RECTILINEAR MOTION OR MOTION ALONG A STRAIGHT LINE. For example: Motion of a car along a straight line.

### Curvilinear Motion

Motion along a curve line is known as CURVILINEAR MOTION. For example: Motion of car or any moving object along a curve line.

### Circular Motion

Motion along a circle is known as CIRCULAR MOTION. For example: Motion of cyclist along a circular park.

## Speed

Distance covered by an object in unit time is called speed.

*Speed = Distance ÷ Time*

Speed may be divided into three types: Uniform speed, Non-Uniform Speed and Average Speed

### Uniform Speed

If an object covers a fixed distance in each unit of time the motion is known as UNIFORM MOTION or UNIFORM SPEED.

### Non-uniform Speed

If an object does not cover a fixed distance in each unit of time the motion is known as NON-UNIFORM MOTION or NON-UNIFORM SPEED.

### Average Speed

Total distance covered divided by total time taken is known as AVERAGE SPEED.

*Average Speed = Total Distance Covered ÷ Total time taken*

Speed is also known as VELOCITY.

## Review Question:

Question 1: A car covers a distance of 100 km in 5 hour, calculate its speed.

**Answer:** Given, Total distance = 100 km

Total time taken = 5 hour

We know that, Average Speed = Distance ÷ time

*= 100 km ÷ 5 hour = 20 km per hour*

Question 2: A car covers 20 km in the first hour and cover 30 km in the last 4 hours. Find its average speed.

**Answer:** Given, Total distance covered = 20 km + 30 km = 50 km

Total time taken *= 1 hour + 4 hour = 5 hour*

We know that, *Average Speed = Distance ÷ time*

*= 50 ÷ 5 = 10* km per hour