4th Class Science Force, Work and Energy Work

     Work

When force is used to move an object from its position, we say that work is done.

To move a table from its one positions to another, we require to apply force on the table. You must have pushed a chair many a times. Why the chair moves? The chair moves because of the force applied by you. You apply the force on the chair and move it from its original position to a new position of your choice. This is the process of doing work.  

    Work done by moving an object  

Work is always done by a force. We often name the agent that has applied this force and say that the agent has done work.

When a girl pushes a notebook on the table, we say that the girl has done work on the notebook. Actually the work is done by the force exerted by the girl.

         Energy

Any kind of work can only be done when we have the energy to apply force. Energy can also be defined as the ability to apply force which in turn does the work.

Reading, writing, sitting, eating, playing these are some activities that we? All do. Now think of activities like climbing, riding a bicycle, carrying load, and lifting heavy items. To do all those works, even the simplest one, we need energy. We use energy even while we are sleeping. Energy is also required by matter to change its states. We need heat energy to change water into vapor. Ice is changed into water, which again requires energy.

Changing state of matter

Energy is present in different form like heat energy, light energy, sound energy, electrical energy, mechanical energy, chemical energy and nuclear energy. Energy has the ability to be converted from one form to another.