Work and Energy | CBSE Class 9 Science | Future Classes
top of page

Unlock the Secrets of Work and Energy with Future Classes

Work and Energy is an important concept in CBSE Class 9 Science. Learning about this topic is essential for understanding the world around us. To help students understand this topic, notes and other resources are available for download on our website. These notes provide an in-depth explanation of concepts such as kinetic energy, potential energy, and the law of conservation of energy. We also provide example questions and solutions to help students practice and apply their knowledge. Download our CBSE Class 9 Science notes today and start exploring the fascinating world of work and energy

Our website offers a wide selection of PDF downloads for CBSE Class 9 Science students. Whether you are studying work and energy or any other topic, our PDF notes will provide you with the most comprehensive and up-to-date information. Our PDFs are easy to download and print, allowing you to study anywhere and anytime. With our PDF notes, you can get the head start you need to ace your Science class

Chapter 10 Work and Energy

Work

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

formula for work.

Work is a scalar quantity.

Unit of work is Newton meter or Joule.

1 joule

defination of 1 joule.

When a force of 1 Newton moves a body through a distance of 1 meter in its own direction, then the work done is 1 Joule.

Energy

The capacity of doing work is known as energy.

Energy is a scalar quantity.

Unit: The SI unit of energy is Joule (J) and its bigger unit is kilo joule (kJ).

1 kJ = 1000 J

Forms of Energy

Main forms of energy are:                      

  1. Kinetic energy  

  2. Potential energy

  3. Heat energy

  4. Chemical energy

  5. Electrical energy

  6. Light energy

Sum of kinetic energy & potential energy of a body is called mechanical energy.

Mechanical energy

The energy controlled by a body on account of its motion or position is called mechanical energy.

Kinetic Energy

The energy of a body due to its motion is called kinetic energy.

Examples of kinetic energy

  • Running water

  • Flowing wind

  • A moving car

  • Flying aircraft

Formula for Kinetic Energy

If an object of mass ‘m’ moving with uniform velocity ‘u’, it is displaced through a distance ‘s’. Constant force ‘F’ acts on it in the direction of displacement. Its velocity changes from ‘u’ to ‘v’. Then acceleration is ‘a’.

formula drive for kinetic energy.

Potential Energy

The energy of a body due to its position is known as potential energy.

Examples:

  1. Water kept in dam: It can rotate turbine to generate electricity due to its position above the ground.

  2. Bent string of bow: Potential energy due to change of its shape (Deformation) released in the form of kinetic energy while shooting an arrow.

Potential Energy of an Object on a Height

If a body of mass ‘m’ is raised to a height ‘h’ above the surface of the earth, the gravitational pull of the earth (m × g) acts in downward direction. To lift the body, we have to do work against the force of gravity.

formula drive for potential energy.

Law of Conservation of Energy

“Energy can neither be created nor be destroyed.”

formula for law of conservation of energy.

Power

“Power is defined as the rate of energy consumption.”

Or

“Power is defined as the rate of doing work.”

formula of power.

Unit of Power

unit of power.

1 watt

defination of 1 watt.

Power of Electrical Gadget

The power of an electrical appliance tells us the rate at which electrical energy is consumed by it.

Bigger unit of Power

Bigger unit of power is called Kilowatt or KW.​

1 Kilowatt (KW) = 1000 Watt = 1000 W or J/s

Commercial Unit of Energy

Joule is very small unit of energy and it is inconvenient to use it where a large quantity of energy is involved.

For commercial purpose, bigger unit of energy is Kilowatt hour (KWh).

1 KWh

​1 KWh is the amount of energy consumed when an electric appliance having a power rating of 1 Kilowatt is used for 1 hour.

Relation between Kilowatt hour and Joule

1 Kilowatt hour is the amount of energy consumed at the rate of 1 Kilowatt for1 hour.

relation between kilowatt hour and joule.

Our website offers a wide selection of PDF downloads for CBSE Class 9 Science students. Whether you are studying work and energy or any other topic, our PDF notes will provide you with the most comprehensive and up-to-date information. Our PDFs are easy to download and print, allowing you to study anywhere and anytime. With our PDF notes, you can get the head start you need to ace your Science class

Work and Energy - Chapter 11, CBSE Class 9

₹75.00Regular Price₹0.00Price
PDF
bottom of page