ENERGY

ENERGY
"The ability of a body to perform work is called Energy".
A body cannot perform work if it does not posses energy.A body cannot perform work more than the amount of energy.
	It is a scalar quantity.
	UNITS OF ENERGY
	(i) Joule (ii) Calorie         [NOTE: 1 Calorie = 4.2 joule.] (iii) KWatt-Hour
	TYPES OF ENERGY
	There aree numerous types of energy such as:  Heat Energy  Light Energy  Sound Energy  Nuclear Energy  Chemical Energy  Electrical Energy   Solar Energy  Wind Energy  Kinetic Energy  Potential Energy etc. etc.
	POWER
	"The rate of work done of a body is called Power".
	AVERAGE POWER
	Average power of a body doing work is numerically equal to the totla work done divided by the time taken to perform the work.
	MATHMATICALLY
	Power = Work done/time Power = Work/t but [work = Fd] therefore Power = Fd/t
	UNITS OF POWER
	(i) watt                     [1 watt = 1joule/sec ] (ii) Kilo watt               [1Kw = 1000 watt] (iii) Mega watt (Mw)    [1Mw = 106 watt] (iv) Horse power         [1Hp = 746w]
	POTENTIAL ENERGY
	INTRODUCTION
	Energy stored by a body by any means is called "Potential Energy".
	DEFINITION
	"The energy stored by a body due to its position in gravitational field is known as ‘Gravitational Potential Energy’".
	FORMULA
	Consider a body of mass "m" placed at a height of "h" from the surface of earth.                                               Force = Weight = W              but displacement (d) = h
	Work done = Fd    OR Work done = Wh  [but W = mg]
	work done = mgh WE know that the work done in lifting the body is stored in the body in the form of Potential Energy. Thus                                                         P.E. = mgh