Chapter 11 Work and Energy

Chapter 11 of CBSE Class 9 covers the topic “Work and Energy”. NCERT's Science Chapter 11 Class 9 notes is created and maintained by Vidyakul's team of academic experts. Vidyakul provides over 2700 exercises and 10 guides.

NCERT Class 9 Science notes in Chapter 11 helps students build a good foundation for exam preparation. A solid foundation beyond grade 9 will go a long way in preparing for grade 10 exams more easily. Students must carefully address all issues related to work and energy. Vidyakul's top academics have prepared a detailed, step-by-step CBSE NCERT notes for Class 9 scientific research. These notes provides students with explanations and tips for solving practice problems. Students can use NCERT notes to increase their confidence and achieve maximum test scores.

CBSE CLASS 9th CH-11

Points to Remember

We have provided some of the crucial points related to Class 9 Science Chapter 11 as mentioned below:

• When a force causes displacement in a body in its direction, it is said to be doing work. It is a scalar value.

• When the displacement is perpendicular to the direction of the force, the work done is zero.

• Mechanical energy is defined as the sum of kinetic and potential energy.

• The watt is the SI unit of power (W). When 1 J of work is completed in 1 s, the power is said to be 1 W.

• The unit of energy is the same as the unit of work, namely the joule (J).

• 1 kW h1 kW h is the energy consumed in one hour at a rate of 1 kW1 kW. It is a commercial unit of energy and equals 3.6106 J3.6106 J.

Topics and Sub-topics

Chapter 11 of the 9th grade science course will help students understand topics closely related to the phenomenon of work: energy and force. Students then learn about the scientific concept of work and the effects of sustained forces on work. This is followed by the concept of energy, and students explore different forms of energy such as potential and kinetic energy.

In this topic, students learn more about Strength, Might, Energy and their relationship. For effective study, students are encouraged to review all topics and subtopics in Year 9, Chapter 11 in the table below.

Below-mentioned is the list of topics present in Class 9 Science Chapter 11:

Sr No	Topic Name
11.1	Work
11.1.1	Not Much ‘Work’ in Spite of Working Hard!
11.1.2	Scientific Concept of Work
11.1.3	Work Done by a Constant Force
11.2	Energy
11.2.1	Forms of Energy
11.2.2	Kinetic Energy
11.2.3	Potential Energy
11.2.4	Potential Energy of an Object at a Height
11.2.5	Are Various Forms of Energy Interconvertible
11.2.6	Law of Conservation of Energy
11.3	Rate of Doing Work
11.3.1	Commercial Unit of Energy

Few Important Questions

• What is the definition of ‘Kinetic energy’?

Kinetic energy is a form of energy that an object or a particle has by reason of its motion.

• What is the definition of ‘Potential energy’?

Potential energy is the stored energy that depends upon the relative position of various parts of a system.

• What is ‘Power’?

Power is the amount of energy transferred or converted per unit time.

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