comparison of linear and rotational motions

Motion means the movement of any object. If an object is moving from the fixed point to another then, it is said to be in motion. So, whenever the object is changing its position it covers some distance. The total path covered during the motion is known as distance. It requires only magnitude. The shortest distance between the initial point and final point is known as displacement. It requires both magnitude and direction. Some of the examples of motion can be seen in our day-to-day life like running, moving from one place to another, etc. There are more such examples. Objects can move in different paths like straight path, curved path or in a zig-zag way. According to the path of the object we can classify the motion in different ways. Here, we are going to read two most important motions: linear motion, rotary motion, linear motion system, linear to rotary motion and vice-versa.

Motion is said to be the movement of any object, body, or particle in any direction with respect to time and reference point. Time, speed, distance and displacement are the terms in which motion can be defined. Motion exists in almost everybody in the universe. Even an atom has constant motion. There are different types of motions, some of them are

• Linear motion

• Rotary motion

1. Oscillatory motion

• Linear motion 

When an object is moving in a straight line or a curved path from one point to another is said to be in linear motion. Only one coordinate axis is required in linear motion. According to the path covered by an object linear motion is further subdivided into two motions.

• Rectilinear motion
• Curvilinear motion

Rectilinear motion: The path covered by an object is a straight line

Curvilinear motion: The path covered by an object is a curved line.

Types of Linear motion

When an object moves in a straight line then it is in linear motion. Linear motion is of two types i.e.

1. Uniform linear motion and 

1. Non-uniform linear motion.

• Uniform linear motion:

When the speed of an object is constant and acceleration is zero then the object is said to be in uniform linear motion.

• Non-uniform linear motion:

When the speed of an object is not constant and it has some acceleration then the object is said to be in non-uniform linear motion.

Rotational motions

We can observe rotational motion in a machine, a celestial body, or while playing our favourite sport. Since each particle of the body moves identically, it becomes crucial to analyse how different particles move in a rigid body while undergoing rotation. 

Before diving deeper into the rotational motion examples, let’s clear a few concepts integral to the rotational movement of particles:

Moment of Inertia: In rotational motion, the moment of inertia is the magnitude by which a rotating object opposes its motion. Therefore, it is also referred to as the rotational inertia of the object. 

The unit of rotational moment of inertia is kg/m2. The moment of inertia of a rigid object rotating about its axis can be given by the below formula: 

Here, m1, m2, and m3 are the masses of any three particles of the rigid object, and r1, r2, and r3 are their respective distances from the axis of rotation.  

Radius of Gyration 

An object’s radius of gyration is defined as the root mean square of the distance of the particles from its rotational axis. It is usually written as K in mathematical formulas and relations. It can be given by the below equation:

If we multiply an object’s mass with the radius of the gyration square it is equal to the rotational inertia of the object. 

Therefore, I = MK2 

When we speak about rotational motion in physics, two theorems are of utmost importance. These theorems are perpendicular and parallel axis theorems. Let’s discuss them one by one. 

Oscillatory Motion

Oscillatory motion is also a type of motion, as we’ve discussed linear motion and rotary motion, let us discuss Oscillatory motion  When a body moves around its mean position i.e. to and fro, then the motion is said to be linear motion. One of the easiest examples of oscillatory motion is the pendulum of a clock as it moves to and fro from its mean position. 

Conclusion

So in this article, we have studied linear motion, rotary motion, and also discussed oscillatory motion. So, here giving some more examples of motion to understand properly about it. For example, bikes moving from one place to another place, the flow of air in breathing, running of horses, swimming of water animals in sea or ocean. We can define the motion of the object by noticing the path of the object. Whether the object is in circular motion or rotary motion.  Motion has more types like, projectile motion, rectilinear motion, rotational motion and many more. These motions can also be found by the paths of objects.