Energy due to position is called potential energy. It is represented as P.E.It is a scalar quantity.Its unit is joule.P.E is the type of mechanical energy,which is define as:Energy due to motion and position.
Before we discuss the explanation of P.E,we give some mechanical energy examples.
Examples of mechanical energy
- Moving wind when it turns windmill
- Aeroplane moving in air
- Running water in rivers or streams
- Hammer in air
- Football in motion
- Flying kite
Explanation of P.E
When a diver jumps off a high board into a swimming pool,he hits the water moving pretty fast,with a lot of kinetic energy.Where does that energy come from?The answer is that gravitational force (his weight) does work on the diver as he falls.The diver’s kinetic energy-energy associated with his motion-increases by an amount equal to work done.
However,there is a very useful alternative way to think about work and kinetic energy.This new approach is based on the concept of potential energy,which is energy associated with the position of a system rather than its motion.In this approach,there is gravitational potential energy even while the diver is standing on the high board.Energy is not added to the earth diver system as the diver falls,but rather a storehouse of energy is transformed from one form (potential energy) to another (kinetic energy) as he falls.And also we will see how the work energy theorem explains this transformation.
If the diver bounces on the end of the board before he jumps,the bent board stores a second kind of potential energy called elastic potential energy.We will discuss elastic potential energy of simple systems such as a stretched or compressed spring.(An important third kind of potential energy is associated with the positions of electrically charged particles relative to each other.)
We will also prov e that in some cases the sum of a system’s kinetic and potential energy,called the total mechanical energy of the system,is constant during the motion of the system.This will lead us to the general statement of the law of conservation of energy,one of the most fundamental and far reaching principles in all of science.
Potential energy formula
P.E = mgh
Examples of P.E in everyday life
- When we stretch a rubber band or lift a stone to a some height,energy is stored in these objects.This energy is called potential energy.
- A brick on the ground cannot do any work.But when we raise the same brick ,energy is stored in these objects.This energy is called potential energy.
- The energy in the wound up spring of a toy car is potential energy.This energy can causes the toy car to move.
- When we put a stone in the sling of a catapult and stretch its rubber ,potential energy stores in it.This energy can throw away the stone.Similarly the water stores in the dam has potential energy.
5 different types of P.E
- Chemical energy
- Stored mechanical energy
- Gravitational energy
- Nuclear energy
- Elastic potential energy
Chemical energy is a form of potential energy produced during chemical reactions.It is stored in food,batteries and fuels such as coal ,petrol and natural gas.Food ,fuels and batteries releases chemical energy as result of chemical reactions.Electric energy is obtained from electric cells and batteries as a result of chemical reaction between various substances present in them.Animals get heat and muscular energy from the food they eat.
Stored Mechanical Energy
Mechanical energy is energy stored in the objects by the application of force.Compressed springs and stretched rubber bands possess stored mechanical energy.
Gravitational energy is energy stored in an object due to its height.When we raise a brick up to some height ,it possesses gravitational energy.
If you want to understand P.E visually then watch this video.