Introduction to Motion: Definition and Examples

Motion can be described as the act of change in the position of an object, with respect to time. A person moving from one place to another, a phone falling off a surface, vehicles moving, rattling of windows, striking the carrom coins, etc. all are examples of motion. Everything in this universe is in motion, from the air we breathe, to the earth rotating are all acts of motion. All the galaxies are in the state of continual motion. 

Even the nano or the fundamental particles of a matter that are the protons, electrons and neutrons are in continuous motion. All the physical events in the world follow the laws motion in some way. Motion is motion, irrespective of the speed, time, distance or displacement. Students must gain in-depth and strong conceptual understanding in Motion. Motion is mainly determined in the following terms:

• Speed
• Distance
• Time
• Displacement

Understand Distance and Displacement

Both distance and displacement can describe the motion or a change in the position of an object. When you want to know the distance between two points, X and Y, you may not be able to give an exact distance, since it may depend on the path taken. However, displacement can be given in definite terms since it is the straight line joining the points X and Y. Displacement is the shortest distance to be covered between the two points in question. 

Both displacement and distance can be used to express the change in position. If a question arises that how far is X from Y, we may not be able to provide a proper distance, since it depends on the route covered between the two places. However, if the two locations are such that they can be connected with a straight line, it is displacement and a definitive answer can be given for the question.

Types Of Motion

Objects do not just move in a straight line but also in many different ways. Some objects move across a curved course, some in a straight line, and some more in a random or haphazard manner. Based on the nature of the motion of an object, motion is divided into three types:

• Rotary motion
• Linear motion
• Oscillatory motion

What is Linear Motion?

An object is said to be in linear motion, when it moves from one point to another, in either a straight line or along a curved path. Depending on the path of motion, linear motion is further classified as follows:

• Curvilinear Motion: In this type of linear motion, the path across the motion is curved.
• Rectilinear Motion: In this type of linear motion, the path across the motion is a straight line.

The examples of linear motion are the motion of a car, a ball, the motion of an airplane, etc.

Rotatory Motion

Rotatory motion is the motion that occurs when a body rotates on its own axis. A few examples of the rotatory motion are as follows:

• The motion of the earth about its own axis around the sun is an example of rotary motion.
• While driving a car, the motion of wheels and the steering wheel about its own axis is an example of rotatory motion.

Oscillatory Motion

An object is said to be in oscillatory motion when the motion is about its mean position. Read the examples below to understand oscillatory motion: 

• When a person sitting on a swing is pushed, the swing moves forward and backward about its mean position, i.e. about its original position.
• The pendulum of a clock is another example of oscillatory motion. The pendulum moves sideways about its actual/mean position.
• The string of a musical instrument, when strummed, it moves or vibrates about its mean position.

Periodic Motion

Periodic motion is the kind of motion in which the action of motion is repeated at a fixed intervals. To understand periodic motion better, consider the following examples: bouncing of a ball, a rocking arm chair, a swing in motion, a vibrating tuning fork, etc. 

Important Formulas on Motion

The speed of an object/entity is the rate at which the object changes its position from its starting point to the destination. Speed is measured as distance (in meters)/ Time (in seconds) or m/s. This is how speed of an object is calculated. The most basic and important formulas for motion are given below:

1. Speed = Total distance traveled/ time taken to complete the travel
2. Velocity = Displacement/time

What is Velocity?

Velocity is nothing but the speed in a given direction. While speed describes how fast an object is moving from one position to another, velocity provides us with both the speed and direction of the object in motion. 

What is Acceleration? 

Acceleration can be defined as the rate of change of velocity with respect to time. It is the rate at which an object gains speeds or slows down. If the object speeds up, it is said to have positive acceleration. If the same object slows down, it is called negative acceleration.

We hope this article on Introduction to Motion has made it easier for you to get a footing in the concept of motion. 

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