A Brief Note on Motion in a Straight Line

When the position of an object is changed with respect to time, it is called motion. When a particle moves along a straight line, motion is called motion in a straight line. It is also defined as 1D motion.

Motion

Motion is defined as the change in the position of an object when compared to time. Let’s say a book falls off the table, water flows from a tap. Even the air that we breathe is considered to be in motion. Everything in the world moves. Motion is an important topic in the subject matter of physics. This matter is usually described in terms of distance, displacement, time and speed. Of these four, distance and displacement are used to explain the change in the position through motion.

In our day-to-day life, we see numerous objects moving around us. More examples of motion are:

• The water flowing out of the tap

• People walking on the streets

• Vehicles running on the roads

• Birds flying in the air

• A pen falling off a table

• A fruit falling from a tree

The shortest distance between the initial and final points is known as displacement. 

Types of motion

We have observed various objects move in different ways. Some things move in a straight path, some act in a curved direction, and others differently. Motion is categorised into three types according to the nature of the object’s movement. The three types are:

• Rotatory Motion

• Linear Motion

• Oscillatory Motion

Rotatory Motion

This type of motion exists when an object is travelling in a circle, it usually occurs when the object is rotating around its place or axis. This was the first type of motion that was discovered by scientists studying motion. When we look at a three-dimensional object, it may have an infinite rotation axis. An example of rotatory motion is the movement of wheels and also the steering wheel of a car when driving. It is the same thing that happens with the engine of a car as it moves in the same place.

Linear Motion

The motion in which the object moves from the initial point to the final is either curved or straight. Depending on the path of motion, linear motion is divided into two categories:

• Rectilinear Motion – When the path of motion is straight

• Curvilinear Motion – When the path of motion is curved

Some examples of this type of motion are the motion of a football, a train or a car on the road.

Oscillatory Motion

The motion of a body around its mean position is known as oscillatory motion. For example, the pendulum of a clock, the swinging of a swing, etc. 

Motion in a Straight Line

An object is said to be in motion when it changes its position in relation to its surroundings with time. With time, the object also changes its position. Linear motion is known as motion in a straight line. It is a one-dimensional motion. 

Linear motion in a straight line is further divided into two categories:

1. Uniform linear motion has zero acceleration or constant velocity.

2. Non-uniform linear motion has non-zero acceleration or variable velocity.

Linear motion is a type of one-dimensional motion. It is suggested in Newton’s first law that “an object will remain in motion unless or until an external force is applied on it”. 

Based on the nature of displacement, linear motion is classified into:

1. Uniform motion

2. Non-uniform motion

Motion in Straight Line Equations

v = u + at

s = ut + ½ at2

v2 = u2 + 2as

v = final velocity

u = initial velocity

s = displacement

a = acceleration

t = time

These could also be referred to as the kinematic equations for uniformly accelerated motion.

Conclusion

In this article, we went through the concept of motion in a straight line and covered various types of motion, their formulas and examples. We have read that the change in the position of an object to time is called motion. In simple words, if a body is moving, it is described as motion. The motion might be slow or swift, but it will exist in every moving body. Motion can be described in terms of time, speed, displacement and distance.