CHAPTER 1.2Pressure in Fluid Systems

STATES OF MATTER AND KINETIC 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

WHAT 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

DENSITY AND PRESSURE

Density- the amount of a material per unit volume

Differences in density causes things to float or sink.

= r m / V

Weight Density- comparison of an object’s weight to volume

rw= W / V

Pressure- a force exerted over a surface

P = F / A

P = rw x h

PRACTICE PROBLEMS

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 ( r = 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.