Work and Energy

Work - 
                "Work is done by a force only when this force ,acting on a body,produces some displacement of the body in its own direction."

Factors affecting the work done-   
                                                                     The work done by a given force depends on two factors:

• amount of force applied.
• displacement of the object produced by the applied force.  

 Energy-

                  When we come home after playing,we are tired.We do not feel like doing anything.In other words,our capacity to do work has decreased.When we take some refreshment,we feel active and energetic again.In other words,our capacity to do work has increased.we consider the capacity to do work as energy.Thus,energy is the capacity to do work.

             It is energy,stored in arm muscles,that enables a player to throw a ball.The energy ,stored in a battery,enables a radio to play music,or a toy car to move.The player uses the energy,stored in her or his muscles,whereas the radio uses the energy stored in a battery.We regard energy as present,or stored,in different forms.We now talk about some of these forms of energy.

Forms of Energy-

    

1) Mechanical Energy-

                                                

concrete breaks when we hit by a hammer

If we let a stone drop from a height on an earthern pot,what is likely to happen? The pot is likely to break.Similarly,when we raise a hammer to the height of our shoulder and hit it on a concrete block,it breaks.Here the stone and the hammer,can be regarded as possessing energy due to their raised height.This type of energy is called potential energy.We think of this as the energy stored in objects,due to their position and condition.

A fast moving ball can break a glass window

   We can easily realise that moving objects also possess energy.For example,a fast moving ball can break the glass pane of a window.Flowing water can move a log of wood from one place to another.This form of energy,possessed by an object due to its motion,is known as the kinetic energy of the object.

If an object possesses either potential energy or kinetic energy or both,we say that the object has mechanical energy.

Heat energy- 

                                   Let us boil some water in a                                                      container covered with a lid and observe what happens to the lid.The lid is seem to move up and down.The steam formed due to the 

steam formed moves the lid

                                         heat.Heat is one of the most common forms of energy.The sun's heat warms warms the earth and this enables it to support a vast variety of life.

Chemical Energy-

burning of wood by a matchstick

                                       When we strike a matchstick against a specific portion of a matchbox ,what happens?  A spark is produced which gives out heat and light.In other words ,the material used on the matchsticks,produces energy when it strikes against a matchbox. This type of energy is called as chemical energy.

Light Energy-
                                          Sun is the main source of light                                               energy .It is sunlight that                                                        helps us to see everything clearly.It is also used by green plants to make their food. CFL,tubelight are the man-made sources.

sun-main source of light energy

Sound Energy-

                              Sound is a form of energy . It produced when an object vibrates.For example when we strike a drum with drumsticks it vibrates and produce sound . This type of energy is called as sound energy.

          Electrical Energy-

                   

It is now difficult  for all of us to imagine a life without electricity.In our day to day life.Electricity is used to run different home appliances like TV and many others.An electric bell sound when electricity flow through it due to electrical energy.