1. Properties of Fluids Displacement SCI 8: Fluids Unit Curriculum Outcomes Addressed: - Analyze quantitatively the density of various substances and suggest explanations for discrepancies in data, such as the measurement of the volume of irregular objects by water displacement (210-7, 307-11)

2. We will study the following properties of fluids: 1.Density 2.Buoyancy (Floating and Sinking) 3.Displacement (Archimedes’ Principle) 4.Viscosity 5.Pressure (Pascal’s Principle)

3. Key Terms Displacement: “The removal of something by something else that takes its place.” Archimedes’ Principle of Displacement: “The volume of the fluid displaced by a sunken object equals the volume of that object”

4. Displacement: Archimedes’ Principle Archimedes’ principle states that “ The volume of the fluid displaced by a sunken object equals the volume of that object” also, the mass of the fluid that is displaced by that object is buoyant force that is acting on that object.” LEGO VIDEO

5. Archimedes and the Crown Archimedes (a Greek mathematician/physician) was given the task of determining whether the King’s crown was made of pure gold or not. One day, he was sitting in the bathtub and realized that the level of the water in the tub rose as he got in; he ran out of the bathtub screaming “EUREKA” – he had just discovered that he could use the principle of displacement to figure out whether the king’s crown was made of pure gold or not by comparing how much water was displaced by the crown and an equal mass of pure gold. Archimedes found that the crown displaced more water than the pure gold of the same mass. This meant that the crown was not made of pure gold, but rather, a mixture of gold and a lighter material (silver).

6. Review Questions Copy and complete these sentences by choosing the correct word from each pair: 1.Silver is lighter/heavier than gold, so to make the crown the same mass, less/more silver was needed. 2.The crown took up less/more space and pushed out less/more water than the lump of gold because less/more silver was needed to replace the gold that the goldsmith took.

7. Review Questions Imagine that Archimedes weighed the new crown and found that it had a larger mass than the original lump of gold. The goldsmith insists that he has used extra gold to perfect the design. 1.What do you think Archimedes would have done next? 2.How do you think it would be possible for Archimedes to prove that the crown has some lighter metal in it?

8. DISPLACEMENT ACTIVITY