Question

why don't we use body parts for mesurment ?

Answer 1

Humans and other animals body parts vary widely in size and shape. Thus, if we were to use body parts as a "standard of measurement" the idea of standard measurement wouldn't exist.

Say we are using "hands" as a measure. One individuals hand will likely not be the same as another persons hands, therefore if we were building a wall 50 hands tall, the actual sizes of the wall would be different.

Answer 2

Ans: Body parts are not a reliable instruments for measurement. This is because different people might have body part of different sizes. This can lead to inconsistent measurement. Therefore, body parts should not be used as a measuring instrument.
    ■  Eg.- A child measures length of a table 5 hand spans and an adult measures the length of the same table as 4 hand spans. This is inconsistency in the results.


Hope it's help you!