The concept of motion or rest is always relative to a specific point, known as the origin. Changes in position, therefore, can be described using two quantities: distance and displacement. But what distinguishes these two terms?
Simply put, distance refers to the total path length covered during motion. It can only be represented by magnitude. Displacement, however, signifies the shortest distance between the initial and final positions. It requires both magnitude and direction for its complete representation.
Motion can be defined as the change in an object's position over time. Whether it's a book falling off a table, water flowing from a tap, or windows vibrating due to the wind, all these phenomena exhibit motion. Even the air we breathe is in constant motion! Everything in the universe, from the smallest atom to the largest galaxy, is in some form of motion. This continual motion is a fundamental characteristic of our universe, making the study of motion an essential part of understanding the physical world. Motion is typically described in terms of distance, displacement, speed, and time.
Distance
Displacement
Speed
Time
As mentioned earlier, distance and displacement help describe changes in position. The distance between two points, say A and B, can vary depending on the path taken. However, displacement, being the shortest distance between the initial and final positions, will always be the same, regardless of the path followed. In other words, displacement is the straight-line distance between two points, with a specific direction from A to B.
Let's illustrate this with an example: Consider two cities, A and B, separated by a distance 'd'. A person travels from A to B and then returns to A. We are to calculate the distance travelled and the displacement.
Distance travelled = Total path length covered
= d + d
= 2d
Displacement, being the shortest distance between the initial and final position, will be zero in this case as the initial and final positions are the same.
Now, can displacement ever be greater than the distance covered in a motion? Or can it be equal? Think about it.
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You may have noticed that not all objects move the same way. Some move in a straight line, some follow a curved path, while others exhibit a completely different kind of motion. Depending on the nature of movement, motion can be classified into three types:
Linear Motion
Rotary Motion
Oscillatory Motion
Exploring Linear Motion
In linear motion, particles move from one point to another along either a straight or a curved path. Depending on the path of motion, linear motion is further divided into:
Rectilinear Motion – Here, the path of motion is a straight line.
Curvilinear Motion – In this type, the path of motion is curved.
Examples of linear motion include the movement of a train on its tracks, a football being kicked across a field, or a car driving on the road.
Understanding Rotatory Motion
Rotatory motion is when a body rotates on its own axis. Here are some examples of rotatory motion:
The earth's rotation on its axis around the sun is an example of rotary motion.
The spinning of a car's wheels or the turning of the steering wheel around its axis are examples of rotatory motion.
Diving into Oscillatory Motion
Oscillatory motion is the back and forth movement of a body about its mean position. Here are a few examples of oscillatory motion :
When a child on a swing is pushed, the swing moves back and forth about its mean position.
The pendulum of a clock moves back and forth about its mean position, demonstrating oscillatory motion.
When a guitar string is plucked, it vibrates back and forth from its mean position, resulting in oscillatory motion.
Real-world Examples of Motion
To better grasp the concept of motion, let's consider a few real-life examples.
Everyday activities such as walking, running, or closing a door all involve motion as there is a change in the position of the object (or person) involved.
The process of inhaling and exhaling air involves motion as air moves in and out of our lungs.
Vehicles that transport passengers from one location to another demonstrate motion as the position of the passengers changes.
As per motion definition, it is the change of position of an object with respect to time.
What are the types of motion?
The following are the types of motion: Linear Motion, Rotary Motion, Oscillatory Motion.
What are the types of linear motion?
Types of linear motion are: Rectilinear Motion, Curvilinear Motion.
State true or false: Displacement is measured as the shortest distance between the initial and final position.
TRUE
Give some examples of motion
Examples of motion are: Walking, Running, The flow of air in and out of our lungs, The automobiles that carry passengers from the place of pick up to the destination.