The closed tank of fig. p.2.34 is filled with water and is 5 ft long. the pressure gage on the tank reads 7 psi. determine: (a) the height, h, in the open water column, (b) the gage pressure acting on the bottom tank surface ab, and (c) the absolute pressure of the air in the top of the tank if the local atmospheric pressure is 14.7 ps

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y