C HAPTER 1.2 Pressure in Fluid Systems

S TATES OF MATTER AND K INETIC THEORY Solid - molecules are constantly moving, but they do not move around. They vibrate about fixed positions Liquid - molecules moving faster and slide past one another Gases - molecules move freely about the container Plasma - a gaseous state of matter that contains electrons and ions (charged particles) The most abundant type of matter in the universe. Components of stars and intergalactic matter

W HAT IS A FLUID SYSTEM ? A fluid is any material that can flow, has no definite shape (takes the shape of its container) A liquid or a gas Fluid systems use liquids or gases to operate mechanical devices Pneumatic System- uses a gas Hydraulic System- uses a fluid

D ENSITY AND P RESSURE Density - the amount of a material per unit volume Differences in density causes things to float or sink.  m / V Weight Density - comparison of an object’s weight to volume  w  W / V Pressure - a force exerted over a surface P = F / A P =  w  x h

P RACTICE P ROBLEMS 1. A volume of 500 cm3 of a certain fluid has a mass 550 g. What is the density of the fluid? 2. A graduated cylinder contains a 200 mL of alcohol (  = 0.8 g/mL). Find the mass of the alcohol.

3. Two identical bricks, each weighing 32 N, are placed on a table – one on its end the other on its edge. If the dimensions of the bricks are: 10cm x 7 cm x 15 cm (A)Which brick exerts the force on the table? (B)Calculate the pressure exerted by each brick on the table.