Comparison of Linear and Rotational Motion: Overview, Types, Difference

Comparison of Linear and Rotational Motion: When an object moves from one point to another point in some time, or we can say when an object or a body changes its position with respect to time, then that object is said to be in motion. If it stays at the same position for a long time, then it is said to be at rest or not in motion. There are different types of motion which we usually study in physics, viz. \(\left( 1 \right)\) linear motion, \(\left( 2 \right)\) rotational motion, \(\left( 3 \right)\) circular motion and \(\left( 4 \right)\) periodic motion.

Comparison of Linear and Rotational Motion: Types of Motion

As mentioned earlier, there are four different types of motion –\(\left( 1 \right)\) linear motion, \(\left( 2 \right)\) rotational motion, \(\left( 3 \right)\) circular motion and \(\left( 4 \right)\) periodic motion. Before looking at the comparison between linear motion and rotational motion, let us look into a short introduction of each type of motion

1. Linear Motion

When a body moves on a straight line or by taking a path or by taking some turns from here and there in two dimensions or three dimensions, then that object is said to be in linear motion. It is the simplest type among the four types of motion, and we can say the linear motion of everybody around us in our daily lives. For example, someone walking on a road, the motion of vehicles, etc., are considered to be linear motion.

2. Rotational Motion

When a body rotates about a fixed axis, it can be anywhere on the body, then that object is said to be in rotational motion. It should not move from one place to another; it should just be at its place and keep on rotating on its axis. For example, the tire of a vehicle performs rotational motion about its central axis, the motion of a shaft in a motor, motion of a fan, etc., are considered to be rotational motion.

3. Circular Motion

In this case, the body rotates in a circle around a fixed centre and a fixed radius which determines its curvature. It is a special case of linear motion where the body experiences a different form of acceleration known as centripetal acceleration. Due to a continuous centripetal acceleration, the direction of the object goes on, changing continuously, and the path thus formed becomes circular. Hence, this type of motion is known as circular motion. For example, the motion of electrons around the nucleus, motion of the earth around the sun, motion of a vehicle that moves around a circle, etc., are considered to be circular motion.

4. Periodic Motion

The motion which repeats itself after fixed intervals of time is considered to be periodic motion. Let us take an example of the daily life of a student, he/she wakes up early in the morning, goes to school or college, attends their lectures for a fixed time, reaches back home, studies, have some time to relax, sleep and repeat the whole procedure for the whole week. So, the time period of their motion per day is 24 hrs. This has two other special cases too, first is that if we have a to and fro motion that repeats itself in a fixed interval of time, for example, the motion of a pendulum, then it is said to be in oscillatory motion. In the second case, along with to and fro, if its acceleration is directly proportional to the negative of its displacement, then it is said to be performing the simple harmonic motion. So, every simple harmonic motion is an oscillation, and every oscillation is a periodic motion but not vice versa.

Difference between Linear Motion and Rotational Motion

Linear motion is on a straight road, whereas rotational motion is along a rotational axis. Before looking at the comparison between linear motion and rotational motion, let us look into some more detailed differences between both types of motion:

Analogy between Linear and Rotational Motion

Before looking at the comparison between linear and rotational motion, let us look at the analogy between them:

Summary About Comparison of Linear and Rotational Motion

Reading this article, we came to know about an introduction to motion which says that when an object moves from one place to another place, it is said to be in motion. Then we understood different types of motion: \(\left( 1 \right)\) linear motion, \(\left( 2 \right)\) rotational motion, \(\left( 3 \right)\) circular motion and \(\left( 4 \right)\) periodic motion. Every motion has its own parameters and own characteristics, which makes them different from other types of motion.

Then we looked into the difference between linear and rotational motion as linear motion is along a straight line whereas rotational motion is along a fixed axis known as a rotational axis. Then we saw an analogy between linear and rotational motion which shows the equations for similar physical quantities for the different motions.

FAQs About Comparison of Linear and Rotational Motion

Let us look at some of the frequently asked questions about the topic:

Q What is the rotational equivalent of linear motion?
Ans: Rotational equivalent to linear motion is those quantities that are similar in both types of motion. For example, the rotational equivalent of force is torque; linear momentum is angular momentum, mass is a moment of inertia, etc.

Q What are the difference and similarities between linear and rotational motion?
Ans: The main difference between them is that linear motion is along a straight line, whereas rotational motion is along a fixed axis known as the axis of rotation. Other than that, if we talk about similarity, then circular motion connects both of them. In rotational motion, every particle of the rotating body is considered to be performing the circular

Q What are some of the examples of linear motion?
Ans: Some basic examples of linear motion are a bullet shot from a gun, an athlete running along a straight track, etc.

Q What are some of the examples of rotational motion?
Ans: Some examples of rotational motion are a rotating motor, rotating fan, rotating wheel of a vehicle, etc.