1. Using energy:

(i) Energy is the capacity (ability) to do work.

(ii) Unit of energy is the same as work, i.e., joule $(J)$ .

(iii) Work is said to be done by a force when it causes displacement in a body. It is a scalar quantity.

(iv) Potential energy is the energy possessed by a body on account of its position (gravitational potential energy) or configuration.

(v) Kinetic energy is the energy possessed by a body by virtue of its motion.

(vi) The sum of kinetic energy and potential energy is termed as Mechanical energy.

(vii) Chemical energy, heat energy, electrical energy, light energy, sound energy, thermal energy are some important types of energies.

2. Energy conservation:

(i) Law of conservation of energy states that energy in a system can neither be created nor destroyed. It may be transformed from one form to another form, but the total energy of the system remains constant.

3. Describing energy transfers:

(i) A Sankey energy transfer diagrams can be used to describe energy transfers.

(ii) $Total energy wasted = Total energy input - useful outputs of energy$

4. Finding energy:

(i) Renewable sources of energy are those which can be generated by us or which are constantly being generated by natural processes or whose supply is unlimited. Examples: the sun, wind, flowing water.

(ii) Non-renewable sources of energy are those which were produced in the past by natural processes, whose supply is limited and which we cannot generate ourselves. Examples: coal, petroleum, natural gas.

(iii) Fuels that originated from the remains of dead plants and animals are called fossil fuels. Coal, petroleum and natural gas are fossil fuels. These are conventional, non-renewable fuels. Burning them causes air pollution.

wind	sun	electricity	resource
non-renewable	fossil fuels	renewable

What is biofuel?

Important Questions on Energy

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