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# Physics – 02

വർക്ക്, എനർജി, പവർ എന്നീ പ്രധാന ഭാഗങ്ങളാണ് ഇന്നത്തെ പാഠത്തിൽ ഉൾപ്പെടുത്തിയിരിക്കുന്നത്.

• Law of Conservation of Energy was put forwarded by

Albert Einstein

• The law which states “Energy can neither be created nor be destroyed but can be transformed from one form to another”

Law of Conservation of Energy

• Einstein proposed special theory of Relativity in

1905

• Einstein proposed General theory of Relativity in

1915

• Equation mentioning the relation between matter and Energy

E=mc²

• A work is said to be done if

There is displacement of body in the direction of force applied

• Equation mentioning the relation between Force and Work

W=FxD [D: Displacement]

• Ability to do work is called

Energy

• CGS unit of work

Erg (1 Joule = 107Erg)

• The term Energy was first coined by

Thomas Young

• Mechanical Energy of an object is occurred due to

Its motion

• Two type of Mechanical Energy of an object is

Potential Energy and Kinetic Energy

• Energy possessed by a body by virtue of its position is called

Potential Energy (PE)

• Potential Energy of an object of mass ‘m’ situated at a height of ‘h’ above the ground is

mgh (g: acceleration due to gravity)

• Energy stored in water reservoir of a dam, in a compressed spring etc are examples of

Potential Energy

• Potential Energy of an object at rest on ground is

Zero

• Potential Energy increases as the height

Increases

• Energy possessed by a body due its motion is called

Kinetic Energy (KE)

• Energy changes in a body thrown vertically upwards

Potential Energy increases and Kinetic Energy decreases

• Potential Energy of a free falling body is

Decreasing

• Kinetic Energy of an object of mass ‘m’ moving with velocity ‘v’ is

1/2 mv²

• If the velocity of an object is doubled, its Kinetic Energy becomes

Four times

• If the mass of a moving object is doubled, its Kinetic Energy becomes

Doubled

• A moving stone or moving bullet possesses

Kinetic Energy

• Kinetic Energy of an object is always

Positive

• Examples of Law of conservation of momentum

Rocket propulsion, Jet engine, Fire a pistol etc

• All objects in free fall near the Earth have same

Acceleration

• The acceleration of an object in free fall is independent of its

Mass

• Highest velocity attainable by an object as it falls through air

Terminal Velocity

• An object falls through air will attain its Terminal Velocity when

The force of resistance equal to the gravitational pull on the object

• Rate of doing work is known as

Power (P) [Work/Time]

• 1 Watt =

1 Joule/Sec

• 1 Horsepower =

746 Watts

(To be Continued…)