Work and Energy Class 9 Physics Notes Free| S.Chand Explaination

 Work and Energy Class 9 Physics Notes Free| S.Chand BASED.

Work and Energy which is the part of 2nd term syllabus of class9 is very important chapter of class 9th Physics.

So today I will provide you Free notes of Class9 Physics chapter work and energy for free which is based on S.Chand.

Work and Energy Class 9 Physics Notes Free| 

So now let's get started.

WORK

When we apply some force on an object and the force causes motion then the body is said to be work done.

THERE ARE  3 TYPES OF WORK :

1) POSITIVE WORK

2) NEGATIVE WORK

3)ZERO WORK

1) POSITIVE WORK

=When the displacement occurs in the direction of force applied then the work done is positive.

2) NEGATIVE WORK

When the displacement occurs in the opposite direction of motion the negative work is done.

3)ZERO WORK

When we apply some force on an object but no displacement takes place then there no work or Zero work is done.

*The SI UNIT of work is JOULE (J).

*Work is a scalar quantity.

*It is the dot product of force and displacement.

FORMULA OF WORK

F.S(FORCE *DISPLACEMENT)

Work is a scalar quantity because it is the dot product of force and displacement which are two vector quantities.

Work and Energy Class 9 Physics Notes Free| S.Chand BASED.

                  ENERGY.               

 The ability/capacity to do work is called energy.

The SI Unit of energy is JOULE (J).

Energy can neither be created nor be destroyed.

THERE ARE MANY TYPES OF ENERGY

1) Potential Energy

2) Kinetic energy

3)Neuclear energy

4)Machinecal energy

5) Thermal Energy

E.T.C.

But in this chapter we have to read about 2 types of energy

Which is,

1) Potential Energy

2) Kinetic energy

Work and Energy Class 9 Physics Notes Free| S.Chand BASED.

                    POTENTIAL ENERGY.          

The energy which is posses by a body due to its position is called potential energy.

For example: When we pick a ball to a certain height then the ball attains potential energy.

*EXPRESSION FOR POTENTIAL ENERGY

P.E.= m.g.h

Where,

P.E.= potential energy

m=mass

g=gravitation

h=height

Potential energy is directly proportional to mass, gravitation and height.

Work and Energy Class 9 Physics Notes Free| S.Chand BASED.

                    KINETIC ENERGY.              

The energy possessed by a body due to its motion is said to be Kinetic energy.

Example:  When we move a body then It posses  kinetic energy.

*EXPRESSION FOR KINETIC ENERGY

K.E.=1/2m.v^2

Where,

K.E.= kinetic energy

m=mass

v=velocity

Point to be noted that,

Kinetic energy is directly proportional to square of velocity.

And it is also directly proportional to it's mass.

                            POWER.                         

The rate of doing work is called power.

Or

Work done per unit time.

 *Power is  a scalar quantity because it has only magnitude not direction.

SI unit of power is watt(W).

The formula of Power is

P=W/T

Where,

P=Power

W=work

And T=Time.

The commercial unit of power used in our daily life is kilowatt hour (kWh)

1kWh=10^6 joule

 Another unit used for Power is HORSE POWER (HP).

1Hp= 746watt.

                             That's all.                

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By:Sahil Patel

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