vedic concept of rubbing finger nails for healthy growth of hair

When any two different substances are rubbed to each other,which are rough surfaced,then heat (energy) is produced.
If any two substances are attached together ,then the energy flow is from one body to the other.
If any two substances are conected to eachother by the means of another substance,then the energy flow is from one body to other body,but,the heat can be felt only by the two similar bodys,but not the dissimillar one.
when nails of either the hands are rubbed (similar substances),then energy flow from nails through the body sinus points to the hair as nails and hair are made up of the same substance called keratin.
Hence,by the supply of energy from nails to hair,hair grows healtier.
The converce process may not be possible for it.