Inertia is the basic concept of physics that is explained using the concept of Mass. The inertial concept was first explained by Sir Isaac Newton and the Law of Inertia is explained as any object in a state of rest or in a state of motion always staying in its state of rest or motion until an external force is applied. We can define Inertia in physics as the property of the matter that is linked to the mass of the object.
In this article, we will learn about, What is Inertia, What is Law of Inertia, Examples of the Law of Inertia, and others in detail.
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What is Inertia?
Inertia meaning is the property of any material by the virtue of which any object tends to be in the state of rest or motion and does not change its state of rest or motion until an external force is applied to it. We define the inertia of any object as,
"The property of any object by the virtue of which the object cannot change its state of either in rest or in motion is known as Inertia."
The mass of a body is responsible for creating inertia, the greater the mass of a body, the greater will be the inertia of the body. For instance, It is easy to stop by simply applying braking to a bicycle as the mass of the bicycle is less but it is a lot tougher to stop a bus or a truck, since the mass of a bus or a truck is more. The same is the case when these vehicles are to be started, more effort in bus/truck (since more mass) and less effort on a bicycle (since less mass).
Inertia Definition
Initially, when the concept of inertia was not introduced, Aristotle came up with a hypothesis regarding the objects in motion, which later proved to be false. Therefore, the concept of objects in motion given by Galileo is known as Aristotle's fallacy.
Aristotle's fallacy was based on the everyday observation of objects in motion. Imagine a ball in motion which was thrown some time ago, after some time, the ball has to come to rest. Aristotle presumed this to be a natural phenomenon and not an act of friction and hence claimed that an object in motion always has some external force applied to it, to else it shall come to rest. This concept contradicts the concept of inertia. So we define Inertia in Physcis as the property of the material based on its mass.
What Is Law of Inertia?
The law of inertia also called the first law of motion is the fundamental law of physics that was proposed by famous English Scientist Sir Issac Newton, the law of inertia states that,
"An object in the state of rest or motion always remains in its initial state until and unless external force is applied to it."
Law of Inertia Examples
Various example explaining law of inertia are,
- A ball rolling on a frctionless table in a vacuum rolls for infinity until an external force is applied to it.
- A person standing on a moving bus titls forward when the brakes of the bus are applied.
- Shaking the branches of the tree with fruits makes the fruits to fall on the ground because they are in the state of rest, etc.
Types of Inertia
There are three types of Inertia that are,
- Inertia At Rest
- Inertia In Motion
- Inertia Of Direction
Now let's learn about them in detail
Inertia At Rest
A body remains at rest due to the inertia (opposing force) present inside the object until and unless an external force more than the inertial force is applied to it.
Inertia In Motion
A body in motion remains in motion until and unless an external force (maybe brakes, friction, etc) is applied to the body.
Inertia Of Direction
A body moving in one direction remains in the same direction until and unless some force is applied in order to change the direction of the body.
Galileo’s Free Fall Experiment
The concept of inertia was established by Galileo. It states that if an object is free-falling or rolling down an inclined plane, the distance traveled by the object is directly proportional to the time. Let s be the distance and t be the time traveled then
s ∝ t2
Galileo did an experiment to find this concept. Galileo decided to put the ball on two types of inclined planes as shown in the figure below. The first experiment had both planes equal, it was observed that the ball when rolled down from a certain height reached up to the same height when the surface is extremely smooth. In the second experiment, the other slope is decreased and observed that still the ball reaches up the same height.
Similarly, when the slope of the plane is completely removed, the ball shall reach infinity but due to the presence of friction, it stops after a certain point. Therefore, Aristotle's concept was turned out to be false, since if any friction is not present (assuming), an object in motion shall always remain in motion.
Inertia Exlpain by Galileo
In the conclusion of his free falling experiment Galileo conclude that, Inertia is the internal property of the material and its is responsible for its state of rest or motion and changing the state of inertia requires an external force. This is later confined by Issac Netwon in his Newton's Laws of Motion.
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