Why old system of measurement isn't accepted nowadays ​

We can measure the length of an object by using 'hand span', 'forearm length', or 'footstep' as the units of measuring length. But hand span, forearm length and footstep cannot be used as a standard unit's measurements because their length is not the same for all the persons.

the most common energy conversion is from kinetic energy to potential energy, and then from potential energy to kinetic energy.

later on comes the heat energy, mechanical energy, and other energy conversions.

this energy conversion is so common that we can find it in our day to day lives as well.

- one of the most common energy conversions involves the changing of potential energy to kinetic energy or kinetic energy to potential energy