They travel like waves. Just throw rock at lake you will see wave. When it bumps to barrier barrier reflects some part of it . Not like a line lika a wave
Answer:
A hydrometer is an instrument used to determine specific gravity. It operates based on the Archimedes principle that a solid body displaces its own weight within a liquid in which it floats. Hydrometers can be divided into two general classes: liquids heavier than water and liquids lighter than water
