9th Class Science Notes in English chapter 11 Work and Energy
CBSE Revision Notes for CBSE Class 09 Science Work and Energy Work and Energy: Work done by a Force, Energy, power; Kinetic and Potential energy; Law of conservation of energy for class 09 Science. It includes all main concepts of the chapter in CBSE class 09 Science.
📚 Chapter - 11 📚👉 Work and Energy 👈
🔹 When a force acts on an object and the object shows displacement, the force has done work on the object.
▶ Work = Force x Displacement (FxS)
👉 Sign Convetions for Work Done :-
👉 Two conditions need to be satisfied for work to be done :-
👉 The amount of work done depends on the following factors :-
👉 Forms of Energy :-
✳️Mechanical Energy :-
✳️Kinetic Energy :-
▶ 1. A moving cricket ball
▶ 2. Running water
▶ 3. A rolling stone
▶ 4. A moving bullet
▶ 5. A moving car
▶ 1. Water kept in dam
▶ 2. Wound up spring of a toy car
👉 Types of Potential Energy :-
🔹 On the basis of position and change in shape of object, potential energy is of two type:
1. Gravitational Potential Energy:
🔹 It is the energy possessed by a body due to it position above the ground.
2. Elastic Potential Energy:
🔹 It is the energy possessed by a body due to its change in shape.
✳️Transformation of Energy :-
▶ The change of one form of energy to another form of energy is known as transformation of energy
✳️Law of Conservation of Energy :-
👉 Unit of Power :-
🔹 sI unit of Power is Joule per second or Js1.
🔹 1 watt is the power when 1J of work is done in 1s.
🔹 The bigger unit of power is Kilowatt and represented by kW.
🔹 1kW = 1000W
🔹 Some another units to measure power are:
1 Megawatt = 106 watt
1 horse power = 746 watt
👉 Commercial Unit of Energy :-
1 kWh = 1 kW x 1 h
= 1000 W x 60 x 60 s
= 1000 Js-1 x 3600 s
= 3.6 x 106 J
1 unit = 1 kilowatt hour = 3.6x106 J.