INTRODUCTION / DEFINITIONS :
When a force acts on an object and the object shows displacement, the force has done work on the object .
Two conditions need to satisfied for work to be done :
(i) A force should act on the object
(ii) The object must be displayed .
1 Joule work is said to be done when 1 Newton force is applied on an object and it shows the displacement by 1 meter.
The capacity of a body to do the work is called the is energy of the body.
The various forms of energy are potential energy, kinetic energy, heat energy, chemical energy, electric energy and light energy.
Energy possessed by a body due to its motion. Kinetic energy of an object increases with its speed.
The energy possessed by a body due to its position or shape is called its potential energy.
When an object is raised through a height, work is said to be done on it against gravity. The energy possessed by such an object is called gravitational potential energy.
Energy can neither be created nor destroyed, it can only be transformed from one form to another. The total energy before and after transformation remains the same.
Commercial unit of energy = 1 kilowatt hour (kWh).
Work is said to be done when force is applied on the body and it shows displacement. W = F × s.
Unit of work is Joule.
When 1 Joule work is said to be done in 1 second, the power of the body doing work is said to be 1 watt.
When the density of the object is more than the density of water then the object sinks. If the density of an object is less, then the object will float on the water.
Power is the rate of work doing. S.I. unit of power = watt.
Kinetic energy is the energy present in a body by virtue of its motion. When water is stored in a dam at particular height, we say it has maximum potential energy as the water is present at the height.
The energy stored in the compressed spring is potential energy.