Check & Reflect Answers

2. Check & Reflect Answers 1. There is more space between particles in a gas, so a gas compresses more than a liquid 2. A) a helium balloon is filled with a gas, so it would compress more than a liquid- filled balloon • B) an inflated mountain bike tire would compress more because it is filled with a gas- air! • C) Plastic bubble wrap is full of a gas, air, so it will compress more than a liquid-filled baby teething ring • D). A soccer ball is filled with air, so it would compress more than a solid golf ball.

3. Review Questions • What is buoyant force? • Use the particle model to explain how temperature affects the viscosity of a fluid. • Why is a solid incompressible but a gas is compressible? • Why does an egg sink in pure water in comparison to salt water?

4. Copy This Down Pressure in Fluids- Pascal’s Law 3.5 Confucius Says: A man who fluctuates in church must sit in his own pew.

5. History Lesson (don’t copy) • Blaise Pascal was curious how force is applied to a fluid • Discovered a relationship between water pressure and depth • Pascal was a mathematician

6. Copy This Down Pressure • Pressure– measure of the amount of force applied to a given area; measured in Pascals (Pa). • Pressure = Force/ Area • P= F/A • Units: 1N/m² = 1 Pa • 1000 Pa = 1 kPa • * 1 Pa is very small. It’s the weight of your loose leaf paper on your desk!

7. Copy This Down Example 1 • You have a force of 10N on an area of 2m2. • P=F/A • = 10 N/ 2m2 • = 5 N/m2 • = 5 Pa

8. Example 2 • What is the pressure if the force is 25N and the area is 10m2

9. Example 3 • Find the area created by a force of 10 N and a pressure of 25 pa.

10. Copy This Down Pressure • The greater the depth, the greater the pressure because the weight at the top puts more pressure on the bottom. • Demo!

11. Copy This Down Pressure • Pascal’s Law– when pressure is applied to a liquid in a container, the pressure and force is transmitted equally and undiminished throughout the liquid; enclosed liquid transmits pressure equally in all directions.

12. Copy This Down To Summarize Pascal’s work: • Pressure is a force pushing on a surface • (can be solid, liquid or gas) • The greater the depth of a fluid, the greater the pressure • Force is spread out equally in all directions in a closed system

13. Copy This Down Systems that use Pressure • 1) Hydraulic System– system that uses a liquid (usually water or oil) under pressure to move loads; device that use liquids in a confined space to transfer forces; works according to Pascal’s Law (Fig 3.20).

14. Explanation • The small piston is the input disk • The big piston is the output disk (to lift something) • Which piston has more force if the same pressure is applied?? (p=f/a)

15. Explanation with numbers • Same pressure on both sides= 100 pa • Large disk= 10 m2 • Small disk= 5 m2 • P= f/a • F= p x a

16. Copy This Down Systems that use Pressure • 2) Pneumatic System– system that uses gas under pressure to move loads; device that uses gases in a confined space to transfer forces; works according to Pascal’s Law.

17. Copy This Down Homework! • P. 60 Check & Reflect • 1, 2,3, 4 • P. 61 Assess Your Learning • 1,2,4,6a,6c, 7, 8,10, 11 • UNIT TEST NEXT WEEK!