Energy transformations and energy transfers
● Energy is the capacity of something to do work
● Law of conservation of energy
○ Energy cannot be created or destroyed, it can only change from one form to another
Types of energy / energy stores
● Elastic energy
○ Energy stored in a compressed material is called elastic energy
● Internal energy
○ It is the energy of a substance due to the kinetic energy or movement of its particles
○ Highest in gases
● Chemical energy
○ The energy stored in the bonds of atoms and molecules in an object and it is released in
chemical reaction
● Nuclear energy
○ Energy released from nucleus of an atom
○ Nuclear fission
■ The splitting up of heavier nucleus into 2 or more lighter nuclei and releases a large
amount of heat energy
■ Working principle of atom bomb
■ Fission → Uranium + neutron → Barium + krypton + 3 neutrons + heat
○ Nuclear fusion
■ The process combining 2 or more lighter nuclei to form a heavier nucleus and
release a large amount of nuclear energy
■ Working principle of hydrogen
■ Fusion → Hydrogen nucleus + hydrogen → Helium + heat/light energy
● Gravitational Potential energy(GPE)
○ Energy something gains when you lift an object up and loses when it falls
○ G.P.E → weight x height or mass x height x gravity
○ Higher the object from the ground, the more the GPE
● Kinetic energy
○ The energy of a moving object / energy possessed by an object due to its movement or
motion
○ K.E → ½ x mass x velocity^2
○ Mass = 2K.E/ V^2
○ Velocity = 2K.E/mass
Types of energy transfers
● Light energy
○ Light is an electromagnetic radiation
○ Speed of light is 3 x 10^8
● Thermal/ heat energy
○ Energy transferred between 2 objects at different temperatures
○ It is not continued within the object, it is transferred between 2 objects.
● Electrical energy
○ It is produced by the flow of electrons
○ It is a type of energy transfer
● Sound energy
○ It requests a medium to propagate(transmit)
○ Produced by vibration of objects
● Energy can be transferred through 4 ways
○ Force
■ When a force acts on a body, energy can be transferred between 2 forms
○ Heat
■ Internal energy can be transferred from place to place by the processes of
conduction, convection and thermal radiation
○ Radiation
■ Light and sound carry energy therefore can transfer it between places
(electromagnetic radiation)
○ Electricity
■ Electricity can transfer energy from a power source, delivering it to components
within a circuit
● Chemical energy → K.E +G.P.E + heat energy + sound energy
● Elastic energy → Electrical + thermal energy/ Sound + thermal energy
● In any conversion, the total amount of energy before and after the conversion is constant
● Sankey diagram
○ It is used to show energy transfer
○ It is used to show how much input energy is being used and how much is actually being
wasted
○ The thicker the line, the more the energy
● Efficiency
○ The efficiency of a system is the percentage of energy transferred from the original
store that ends up in the intended form
○ Efficiency → Useful energy output/ Total energy input x 100
○ In percentage
● Generator / Turbine
○ Mechanical → mechanical + electricity
● Thermal power plant
○ Chemical → thermal → mechanical → electrical
● Nuclear reaction
○ Nuclear → thermal → mechanical → electrical
● Windmill
○ Mechanical → Mechanical → Mechanical → Electrical
