Newton's First Law 

Newton for the first time proposed the three laws of motion which form the parts of classical mechanics. Newton's law of motion has helped to describe the relationship between the motion of an object and the forces acting on it. The three laws of motion were first time published by Issac newton in the year 1687 in Philosophiæ Naturalis Principia Mathematica. Among the three law first law talk about the Law of Inertia. In this article, we will learn about Newton's first law of motion. 

Newton's First Law of Motion

According to the first law of motion," A body at rest or in motion continues to remain in the same state unless and until some unbalanced/external force is applied to it. So this law helps to explain why the object's speed is slowed down. Generally, before this theory, it was considered that it is a natural tendency of objects that their speed is slowed down. Simply, it can be said as objects at rest tends to remain at rest and objects in motion tends to remain in motion unless and until some unbalanced or external force is applied to them. This first law of motion is also called as “Law of Inertia”. The first law of motion can, therefore, be simply expressed as: If the net external force on an object is zero, then acceleration is also zero. But if some external force is applied then acceleration becomes non-zero. 

Two conditions on which the first law is dependent-

When the Object is at RestV =0 and  a = 0 (Object continue to be rest)
When the Object is in motionV ≠ 0 and a = 0 (Object continues to be in motion at a constant speed and in the same direction until and unless some unbalanced force is applied)

Application of First Law of Motion

Some of the applications of the first law of motions are-

Travelling in a Bus: You would have felt like jerks while travelling on a bus. The passengers standing in a moving bus experience a sudden forward fall when the driver applies the brakes, this sudden forward fall is due to inertia of motion. Similarly, when a speeding bus stops suddenly, then the body moves forward because the lower part of the body is at rest and the upper part of the body tends to remain in motion. Hence, this causes the passengers to feel a forward push. 

Moving Train: When the train is moving at a uniform speed and the ball is tossed into the air, it goes up and then comes down straight in your hand because it has inertia. 

A Carpet is Beaten to Remove Dust: When the carpet is beaten by the stick, the dust particles start to fall off because as the carpet is beaten, it moves backwards and forward, that is, it comes into motion, but the dust particles continue to remain at rest. This example again explains the law of inertia, the tendency of a body to remain in its initial state.

Fruits and Leaves Fall Off on Shaking Tree Branches: When the tree branches are shaken the fruits or leaves on the trees start to fall off suddenly. As we know when the tree branches are shaken, it comes into a state of motion but the leaves and fruits continue to stay the same due to the inertia of rest and hence they fall down

Related Links-
Newton's Law of Motion Boyle's Law
Charles Law

 

Newton's First Law of Motion- FAQs

Ans. According to the first law of motion," A body at rest or in motion stays in the same state unless and until some external force is applied to it.

Ans. It is also called the law of inertia because inertia refers to the amount of resistance of an object to a velocity change. Velocity change can be in terms of the speed of the object or its direction. Another aspect of inertia is the tendency to continue moving in the same direction line at a constant speed when no forces act on them.

Ans. Law of Inertia was developed by Galileo Galilei in 17th century.

Ans. When the train is moving at a uniform speed and the ball is tossed into the air, it goes up and then comes down straight in your hand because it has inertia.

Ans. When the carpet is beaten by the stick, the dust particles start to fall off because as the carpet is beaten, it moves backwards and forward, that is, it comes into motion, but the dust particles continue to remain at rest. This example again explains the law of inertia, the tendency of a body to remain in its initial state.

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