Properties of Fluids

There are three states of matter: solid liquid gas

Density – the amount of matter that occupies a space Solids Liquids Gas Molecules close together Molecules spread out further Molecules spread far apart

To determine density, you must divide the mass by the volume. D = m÷v

Mass is measured in grams using a triple beam balance…

We can determine the mass of the box using the digital scale or TBB.

Volume of a regularly-shaped object can be measured using a ruler.

Volume = length x width x height 2 cm 5 cm 15 cm

Objects that do not have smooth sides to measure are called irregular-shaped. To measure the volume of these objects we use water displacement.

10 20 30 40 50 Water is put into a graduated cylinder and the volume of the water is measured.

The object is placed in the graduated cylinder. 50 40 30 The volume of the water and the object is determined. 20 10

The first volume is subtracted from the second volume. 40 mL – 29 mL = 11 mL The volume of the object is 11mL.

The density of water is 1g/mL.

If an object with a density of less than 1g/mL is placed in the water, it will float.

If an object with a density of greater than 1g/mL is placed in the water, it will sink.

Can you give an estimation of the density of the alcohol and the oil? DENSITY COLUMN Can you give an estimation of the density of the alcohol and the oil? Water Density = 1g/mL Oil Alcohol

DENSITY COLUMN The density of the oil is less than 1 g/mL. The density of the alcohol is less than the density of the oil. Water Density = 1g/mL Oil Alcohol

Estimate the density of the piece of wood. DENSITY COLUMN Estimate the density of the piece of wood. Alcohol Density = .75 g/mL Oil Density = .96 g/mL The density of wood is .8 g/cm3. Water Density = 1g/mL

Estimate the density of the piece of ice. DENSITY COLUMN Estimate the density of the piece of ice. Alcohol Density = .75 g/mL Oil Density = .96 g/mL The density of ice is .99 g/cm3. Water Density = 1g/mL

Bouyancy The ability of a fluid (liquid or gas) to exert an upward force on an object immersed in it.

Bouyancy and Weight The steel block weighs much more than the wood block. The gravitational force is not enough to sink the wood block. The gravitational force is more than enough to sink the steel block.

Bouyancy and Weight Density of the steel block is more than the water. Density of the wood block is less than the water. One way to know whether an object will float or sink is to compare its density to the density of the fluid in which it is placed.

Viscosity Is the resistance of a fluid to flow.

Viscosity  A fluid with higher viscosity resists motion because of the molecular structure which creates a lot of internal friction within the liquid. A fluid with low viscosity flows easily because its molecular structure results in very little friction when it is in motion.