In the previous lesson, we have learnt what is motion? In this lesson we are going to learn the types of motion with proper examples.

An object is said to be in motion if the body changes its position with respect to its surroundings in the given time.

That was the definition of motion above and we have also learnt the various types of motion. Here we will elaborate each type of motion with examples.

## Types of Motion

Motion can be described in terms of displacement, distance, time and speed. In this universe everything is in motion and different objects move differently. On the basis of that motion is categorised in various types. The different types of motion are,

1. Simple Harmonic Motion: The motion in which acceleration is directly proportional to the displacement and is directed towards the opposite to that of displacement is simple harmonic motion.

Examples,
• A Swing
• A simple pendulum
• Mass spring system
• A steel ball rolling in a curved dish.

2. Linear Motion: The motion of an object along a straight path is called a linear motion. Linear motion is always one dimensional.

Examples,
• Motion of a bowling ball
• Vehicles moving an a straight highway
• A train running on a straight railway track.

3. Reciprocal Motion: Reciprocal motion is a repetitive up and down or back and forth linear motion. Reciprocal motion is also called reciprocation and reciprocating motion.

Examples,
• The wheels of train
• Movement in loud speaker coin
• Internal combustion in engines and pump

4. Brownian Motion: The Brownian motion is the random movement of microscopic particles suspended in a liquid or gas, caused by collision with molecules of the surrounding medium.

Example: Moving particle under a microscope.

5. Circular Motion: Movement of an object along the circumference of a circle or rotation along a circular path is called circular motion.

Examples,
• Satellite orbiting the earth
• Blades of ceiling fan rotating around the hub.
• An electron moving perpendicular to its magnetic field.

6. Curvilinear Motion: Curvilinear motion is  defined as the motion of an object moving in a curved path.

Examples,
• Stone thrown in air at an angle
• Motion of a car along a curved road
• Motion of roller coaster along its curved path.

7. Rotational Motion: A rigid object that is spinning around some rotation axis is called rotational motion or angular motion. In simple words 'the type of motion in which body rotates around an axis is called rotational motion'.

Examples,
• A table fan
• Wheels of a car
• Earth is rotating its own axis
• A windmill rotates when wind blows.

8. Rolling Motion: It is a special type of motion that combines rotation and translation of that object with respect of surface. Such that if ideal conditions exist, the two are in contact with each other without sliding or sleeping.

Examples,
• A round stone rolling downward
• A boy playing with tyre by rolling it
• When your pen drops down from your study bench by rolling itself.

9. Oscillatory Motion: When a body moves to and fro about a fixed point it is said to be oscillatory motion.

Examples,
• The motion of a swing
• The motion of a clock
• A simple pendulum also shows the oscillatory motion.

10. Vibratory Motion: Oscillatory motion is also known as vibratory motion.

11. Projectile Motion: When a body is in free motion (moving through the air without any forces apart from gravity and air resistance) it is called projectile motion.

In simple words, projectile motion was an object going up and coming down.

Examples,
• Water fountain
• Throwing a ball in air

12. Periodic Motion: The motion repeated in equal intervals of time is known as periodic motion.

Examples,
• A rocking chair
• A bouncing ball
• A vibrating tuning fork

### Q1. What is motion?

Ans: An object is said to be in motion if the body changes its position with respect to its surroundings in the given time.

### Q2. What are the types of motion?

Ans: The different types of motion are,
1. Simple harmonic motion
2. Linear motion
3. Reciprocal motion
4. Brownian motion
5. Circular motion
6. Curvilinear motion
7. Rotational motion
8. Rotational motion
9. Rolling motion
10. Oscillatory motion
11. Projectile motion
12. Periodic motion

### Q3. How to measure motion?

Ans: The SI unit of motion is Meter per Second which can be expressed as m/sec.

### Q4. What are the laws of motion?

Ans: There are three laws of motion invented by Sir Isaac Newton.

First Law of Motion: An object at rest will stay at rest, and an object in motion will stay in motion at constant velocity unless an external force is applied on the object.

Second Law of Motion: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

Third Law of Motion: For every action there is an equal and opposite reaction.