In Physics, energy is an indirectly observed quantity that is often understood as the ability of a physical system to do work on other physical system. However, this must be understood as simplified definition as we shall come to know in higher classes that not all energy can perform work. (a) How did the concept of energy emerge ? (b) How much electric energy is generated in a typical lightning strike ? What are the forms to which this energy gets converted ? (c ) What is the kinetic energy of a passenger seated in a moving plane : (i) with respect to the place (ii) with respect to the Earth.

Explanation

The concept of energy emerged out of the idea of Vis Viva (living force) and it was believed that total Vis Viva was conserved.
(b ) 500 mega Joules. Light energy, sound energy, thermal energy, etc. (c ) (i) Zero (ii) Non - zero kinetic energy (and higher total energy).