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NCERT Physics Notes for Class 11 Science Inertia

NCERT Physics notes for class 11 science Inertia,Class 11 Physics,11th science

NCERT Physics Notes for Class 11 Science Inertia

Physics notes for class 11 : Takshila Learning is a unique portal in educational innovations, recognized for providing online classes for CBSE exams with the main objective is to provide the best content that makes preparation easy, cost effective, and efficient for students. We offer animated videos, NCERT solutions, question bank and sample papers designed according to latest pattern of question papers. You can also give our mock tests online. Further, Takshila Learning regularly provides different blogs and articles on important articles, news, and information related to CBSE exams. In the following article, the topic ‘Inertia’ from Class 11 Physics is explained.

Newton’s First Law defines Inertia: According to Newton’s first law of motion, a body remains to be in a state of rest or of uniform motion unless and until it is acted upon by an external force to change its state.This inability of a body to change by itself its state of rest or of uniform motion along a straight line is called inertia of that body.

Newton’s first law is called the Law of Inertia

So, one can define Inertia as “the tendency of an object to stay at rest or in motion”.

Quantitatively, the inertia of a body is measured by the mass of the body that means heavier the body greater is its inertia.

Types of Inertia:

  • Inertia of Rest: The tendency of a body to remain in its state of rest is called Inertia of Rest. That means a body at rest remains at rest and cannot move on its own.


  • A person standing in a bus falls backward with a jerk when the driver starts the bus suddenly. It is because our feet are in touch with the floor of the bus. While our feet go with the bus the rest of the body remains where it is due to inertia and we are thrown backward.
  • When a horse starts running suddenly, the rider on the horse falls backward.
  • When we place a coin on a smooth piece of cardboard covering a glass and strike the cardboard piece with finger suddenly, the cardboard slips away and the coin falls into the glass.
  • When we shake the branch of a tree, its fruits and dry leaves fall down.
  • Dust gets removed when we beat a hanging carpet with a stick.
  • Inertia of MotionThe tendency of a body to remain in its state of uniform motion

in a straight line is called Inertia of Motion.

For animated videos of Inertia & 11th science, click on Physics notes of Class 11.


  • When a moving bus suddenly stops, a person standing in the bus is thrown forward with a jerk.
  • When a horse stops suddenly, the rider falls forward.
  • A person getting out of a moving bus or train falls in theforward Because
  • his feet come to rest on touching the ground and body continues to move due to theinertia of motion.
  • An athlete runs a certain distance before taking a long jump.
  • Inertia of Direction:The tendency of a body to continue its direction of motion.



  • When a car takes a sharp turn, the person sitting inside is thrown outwards because the person tries to maintain his direction of motion due to directional
  • When a stone in circular motion is released, it flies off tangentially.
  • The rotating wheels of any vehicle throw the mud tangentially due to the inertia of direction and the mud guards stop this mud for protecting the clothes of the driver of the vehicle.

it seems contradictory in the day to day observations. Explain.

Ans: In the day to day observations, we observe that a moving body stops after sometime when we do not apply an external force. Since the motion of the body is opposed by two invisible forces, the force of friction between the body and ground and also the resistance of air. If we remove these forces, the body continues to move and never stops on its own.

Want to study the same topic in Hindi, kindly click 11th Class Physics in Hindi.

For more Physics notes for class 11, 11th Science, NCERT solutions class 11th, CBSE guide, sample papers, latest updates from CBSE Board, Enroll with TakshilaLearning

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September 28, 2017

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