Work And Energy Class 9 CBSE Notes - Chapter 11

Work And Energy Class 9 Notes describes the meaning of work and energy, and how they are related to each other. The term work might imply working hard, such as studying for an exam, or a performing a job. However, in science, the term “work” has a very different meaning. It essentially is a term used to define the movement of an object a certain distance using an external force.

What is Work?

Work is the measurement of energy transfer wherein, the object is displaced over a distance by an external force, part of which is applied in the direction of displacement. For instance, work is said to be done when a person pushes a rock over a surface and it has moved some distance. Work is said to be not done when the person pushes a rock and it doesn’t move even an inch.

What is Energy?

Energy, in science, is defined as the capacity to perform work. It can be of various types, namely:

  1. Mechanical energy
  2. Heat energy
  3. Chemical energy
  4. Electrical energy
  5. Light energy

Energy can be transferred between various objects and also change forms. For instance, chemical energy is converted into electrical energy in batteries. Light energy is converted into electrical energy in a solar cell.

Work And Energy Class 9 Notes – Questions

  1. Define Power, mention its SI unit.
  2. If a man pushes a very big tree, will work be done?
  3. What is kinetic energy?

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Practise This Question

Charles Darwin is considered as the 'father of evolutionary biology'.