Work Power And Energy Mock Test || कार्य शक्ति और ऊर्जा मॉक टेस्ट


If a body gets displaced when a force acts on it, work is said to be done. Work is measured by the product of force and displacement of the body along the direction of force.

  • If a body gets displaced by S when a force F acts on it,
  • then the work W= F.S cosθ 
  • where θ = angle between force and displacement 
  • If both force and displacement are in the same direction, then W = F.S
  • Work is a scalar quantity and its SI unit is joule.
Energy: Capacity of doing work by a body is called its energy.
  • Energy is a scalar quantity and its SI unit is joule.

Energy developed in a body due to work done on it is called mechanical energy. Mechanical energy is of two types:

(i) Potential Energy (ii) Kinetic Energy 

  • Potential Energy: The capacity of doing work developed in a body due to its position or configuration is called its potential energy. 
Example: (i)energy of stretched or compressed spring (ii) energy of water collected at a height (in) energy of spring in a watch.

PE of a body in the gravitational field of earth is mgh. 

where m= mass, g = acceleration due to gravity, h-height of the body from surface of the earth.

  • Kinetic Energy: Energy possess by a body due to its motion is called Kinetic Energy of the body.

If a body of mass m is moving with speed v, then kinetic energy of body is mo 1/2 MV^2

Principle of Conservation of Energy:

Energy can neither be created nor can be destroyed. Only energy can be transformed from one form to another form. Whenever energy is utilized in one form, equal amount of energy is produced in other form. Hence total energy of the universe always remains the same. This is called the principle of conservation of energy.

Some Equipments used to Transform Energy:

 SL. NO.


  Energy Transformed



Mechanical energy into electrical energy



Chemical energy into light and heat energy



Sound energy into electrical energy


Loud Speaker

Electrical energy into sound energy


Solar Cell

Solar energy into electrical energy


Tube light

Electrical energy into light energy.


Electric Bulb

Electrical energy into light and heat energy



Chemical energy into electrical energy


Electric motor

Electrical energy into mechanical energy

Power: Rate of doing work is called power.

  • It an agent does W work in time t, then power of agent = W/t
  • SI unit of power is watt named as a respect to the scientist James.

watt = joule/sec.

       1kW = 10 ^ 3 watt        1 MW = 106 watt

Horse power is a practical unit of power. 1H .P.=746 watt.

       1 watt second = 1 watt x 1 second = 1 joule.        
       1 watt hour (Wh) = 3600 joule
       1 kilowatt hour (kWh) = 3.6 * 10 ^ 6 * Joule.
W, kW, MW & H.P. are units of power. 
Ws, Wh, kWh are units of work and energy.

Work, Power & Energy

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