WELCOME

ENERGY

Sources of energy

• Sun• Food

Energy

• Energy is the ability to do work

• Different forms of energy are mechanical energy , heat energy , light energy , etc

Unit of energy

• The unit of energy is JOULE.

Different types of Energy

• Energy are of two types

• 1: Kinetic energy• 2: Potential energy

• The kinetic energy of an object is the energy which it possesses due to its motion.

•  It is defined as the work needed to accelerate a body of a given mass from rest to

its stated velocity..

KINETIC ENERGY

Equation of kinetic energy

•  The kinetic energy of a point object or a non-rotating rigid body depends on the mass of the body as well as its speed.

• The kinetic energy is equal to the mass multiplied by the square of the speed, multiplied by the constant ½. In formula form:

KE=½ mv2

Examples of Kinetic EnergyA moving car

River flowing

A moving body

Example of kinetic energy

• 1. Moving car 2. Moving ball 3. River flowing

• 4. Plane in flight  5. Athlete running  6. Satellite in orbit

POTENTIAL ENERGY

•  Potential energy, or stored energy, is the ability of a system to do work due to its position 

• It is called potential energy because it has the potential to be converted into other forms of energy, such as kinetic energy.

Equation of potential energy

PE=U= mgh

PE=potential energy

m= mass

g= gravity

h=height

Examples of Potential Energy

Water stored in a dam

Gas cylinder

Examples of potential energy

1. Glass of milk

2. Water stored in a dam, store at a height

3. A car parked at the top of a hill 

4. Gas cylinder

Energy

Potential kinetic

Energy possessed by moving object Energy possessed by an object at a height

ExampleMoving carFlowing river

ExampleBook keep on a tableWater store in a dam

Comparison of Kinetic and Potential Energy

PROBLEM

A bullet of mass 0.005 kg is fired from a pistol with a velocity of 200 m/s. what is the kinetic energy of the bullet?

Mass of bullet = 0.005 kg

Velocity =200 m/s

Kinetic energy =½ mv2 =½*0.005*(200)2

=100 J

THANK YOU