A person sucking hard on a thin tube can reduce the pressure in it to 90% of atmospheric pressure. How high can water rise up the tube?

Question

anonymous · Answer

The pressure that the person is able to reduce is responsable for the length of the tube. Given that for fluid, the pressure formula is P=¥gh, where ¥ is the density, g is the acceleration of gravity and h is the height or length of tube. Therefore making h subject of the formula you get P/¥g, but since he reduced the pressure to 90%, it means that he made a pressure of 10%, therefore the length of the tube is 10% of this formula or 0.1P/¥g.