I only know about the Water tank which is the most accurate. You place your body in it, and weights are added I think. Somehow some measurements are gathered to get your body fat weight. Online calculators exist, as well as electronic waves that are sent int your body, the echo is recorded and analyzed.
no.9 indeed all matters are made out of atoms which is smaller than protons and neutrons
Answer: They have different rigidities.
Explanation:
