Work, Power And Energy Class 9 Notes CBSE Science Chapter 11


Work, Power And Energy Class 9 Notes CBSE Science Chapter 11

CBSE NCERT Class 9 Notes Science contains physics, chemistry and biology notes of chapter 11 Work, Power And Energy topics given in textbook are part of Revision Notes for Class 

Science Notes cover an overview of the main given points of every concepts and Topics in the NCERT TextBooks Class 9th Science this Chapter Notes includes topic/concepts wise explanations for all the topic provided in the book such as Work, Energy and its forms, Kinetic Energy and its expression, Potential Energy and its expression, Conservation of Energy, Power, Unit of Energy

Well prepared  CBSE Class 9th Chapter Wise Science Notes will guidance students understand the topics ,concepts and themes covered in all the chapters of Ncert Text book of 9th 

Work, Power And Energy Class 9 Note

Work, Power And Energy Class 9 Notes

(Work) j

The definition of work done may vary in real life and Scientifically. For example, we may consider studying, talking, Singing as work but it is not so in the case of science.

Examples of Scientific work done are 8 Moving a chair from one location to another

Lifting a book from the shelf and placing it on table. pushing a pebble lying on the ground.

Work is done only if

• A force is applied to an  object.

If the object is displaced from one point to another point

Work done by a fixed force  (1)

Work done in moving body is equal to product of force and displacement of body in the direction of force.

work done - Force x Displacement W = FXS Work is a scalar quantity

unit of work = Newton metre or Joule

Q.What is 1 Joule work? (Important for 1 mark) 
A.when a forte of 1 Newton moves a body through a distance of metre in its own direction, then the work done is known as 1 joule. 17 1Nm
Amount of work done depends on following factors: 
(1) Displacement & Graced the displacement, grater is the amount of work & vice-versa.

Negative, Positive and Zero work

 Depending upon the direction of displacement and force applied work can be zero, positive or negative. (i) work dore is positive when a force acts in the direction of motion of the body. (=0°) means angle between force and displacement is zero. WD = FxS Ⓒ means angle (theta)

(1) work dore is negative when a force acts opposite to the direction of motion of body (0 = 180°)

Work done is Zero when a fore acts at right angles to the direction of motion (0 = 90)

Energy (i) The sun is the biggest source of energy. (ii) Most of energy sources are derived from Sun. (ii) Some energy is received from nucleus of atoms and tides. Definition: The capacity of doing work is called energy. The object can gain as use energy depending upon the work done. If an object does some work it loses its energy and if some work is done on an

Energy is a scales quantity.

Unit Joule (1) and its biggest unit is kilo joule (Kg) =

The energy required to do I joule of work is called

1. joule energy.

Types of Energy

Kinetic Energy 

Every moving body have some energy called kinetic energy. The energy of a body due to its motion is called kinetic
energy. Examples of Kinetic energy 
moving cricket ball
Running water moving car

rolling stone

Formula for  Work done we know that va-u-aas )

20.  also know, F=ma (iii) Substitute Gi) and (ii) in (i), we get

W FXS 9 = max v²²


work done = change in

Kinetic Energy 

if u=o (object starts at rest)

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