Property that describes a liquid’s thickness or thinness Property of all fluids liquids and gases
When do we use our knowledge of viscosity on a daily basis?
The time it takes for the fluid to flow from one point to another Predict the flow rate of the following fluids: Paint Water Oil Molasses Vegetable Oil
Different fluids flow at different rates because they have different viscosities Resistance to flow creates internal friction Goes back to the particles The particles of water can slip past each other easier than the particles of oil This is because the particles of oil are more attracted to each other than the particles of water
According to the Particle Model, as the temperature of the material increases attractive forces decrease Increase Temperature= Decrease Attraction Decrease Temperature = Increase Attraction The viscosity of a liquid DECREASES as it is HEATED and INCREASES as it is COOLED
Remember that there is already lots of space between gas particles so attractive forces are low The viscosity of a gas INCREASES as it is HEATED and DECREASES as it is COOLED. That means that temperature has the opposite effect on the viscosity of gases as on liquids
Read pg 36 and do the questions on pg. 37 Questions: 1, 2, 5(a,b,c) Do the question on page 39 1 (a-h), 3(a), 6(a,b,c,g) Make sure you have your glossary complete up to page 49 Do questions on page 49 1, 2,3,4(a,b), 6 When you are done start to make a crossword puzzle with the Words from your glossary.
Buoyancy is the force exerted by a fluid Measured in Newton's (N) Buoyant Force: Upward force exerted on objects submerged in fluids
Floating is when an object doesn’t fall in air or sink in water but stays suspended in the fluid
The key is average density!
Archimedes was required to determine whether a crown made for the king was pure gold Step 1: weighed the crown Step 2: dropped the crown in water to determine the volume of the water displaced. Step 3: Volume of the displaced water is equal to the volume of the object in water. Step 4: Compared the volume of the water displaced by the crown to the water displaced by an equal mass of pure gold Step 5: Crown maker executed
The buoyant force acting on an object equals the weight (force of gravity) of the fluid displaced by the object
Displacement is the measure of the amount of water an object will push out of it’s way when the object is placed in water
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Page 69 Questions: 2, 5a, 5b, Wrap Up pg. 70 Understanding Key Concepts Questions: 1-5, 7, 9 Design your Boat Project Homework
Pressure can be calculated by using the following formula P = F / A [ 1 N/m 2 = 1Pa = kPa ] Measured in Newtons (N) The Unit for pressure is: This unit is also called a Pascal
The following is required for the compression of gas: Gas must be enclosed in a sealed container. Lots of space between particles There must be an external force applied to the enclosed gas Gases are compressible because their particles can be squeezed closer together We say gases are compressible As pressure increases, the volume of the gas decreases.
The particles in solids and liquids can not be pushed closer together Solids and liquids are said to be Incompressible The volume does not change, and the pressure is exerted everywhere on the container's inner surface (this is fluid pressure)
Pascal's principle Pressure applied to an enclosed fluid is transmitted undiminished to every part of the fluid, as well as to the walls of the container.
Air pressure changes with altitude As you climb higher the atmosphere contains fewer particles so the pressure goes down.
The most common device for measuring air pressure is a barometer
Hydraulics is the study of pressure in liquids.
Page 77: Questions: 1, 2ab, 3. Challenge Question 5 Page 84: Questions: 1, 2, 4, 6 Page 85: Questions: 1 a-j, 3, 4, 8 Extra Practice Density and Pressure: - Worksheet