1. Archimedes’ and Pascal’s Principles

3. Archimedes' principle states that the apparent loss in weight of a body that is totally or partially immersed in a liquid is equal to the weight of the liquid displaced. Archimedes supposedly formulated this principle after stepping into a bath and watching it overflow. According to legend, he became so excited that he ran out into the street naked shouting "Eureka! Eureka" ("I've found it! I've found it!")

4. Volume: space taken up by an object The volume of fluid displaced (pushed out of the way) by an object equals the volume of object. Buoyant Force – upward force exerted by fluid The buoyant force on an object equals the weight of the fluid displaced by the object. http://www.youtube.com/watch?v=QvZR7eUvLZA&safety_mode=tru e&persist_safety_mode=1 http://www.youtube.com/watch?v=vJ36urazDu4 http://www.youtube.com/watch?v=eQsmq3Hu9HA

5. Density: ratio of mass to volume If two objects have same volume, which one has greater density: one with more mass OR one with less mass? If two objects have same mass, which one has greater density: one with more volume OR one with less volume?

6. The buoyant force on an object equals the weight of the fluid displaced by the object. Buoyancy is the upward force exerted by fluids. http://www.youtube.com/watch?v=vJ36urazDu4 http://www.youtube.com/watch?v=eQsmq3Hu9H Ahttp://www.youtube.com/watch?v=eQsmq3Hu9H A

7. If the buoyant force > weight, object will float at surface of fluid. If the buoyant force = weight, object remains suspended in fluid. If the buoyant force < weight, object sinks.

8. Freshwater or Saltwater? Air or water? Oil or water? Reading in the Great Salt Lake, Utah http://www.youtube.com/watch?v=TDEz BWjQpQI&safety_mode=true&persist_sa fety_mode=1 http://www.youtube.com/watch?v=wZrW lzHFC4k&feature=fvwp&NR=1&safety_m ode=true&persist_safety_mode=1

9. The weight of the displaced fluid is directly proportional to the volume of the displaced fluid.

10. A piece of solid steel sinks in water, but the shape of a ship’s hull allows it to displace a large volume of water. This creates a large buoyant force, which counteracts the ships huge weight. The effective density of the ship is less than water.

12. Submarines A submarine has a large ballast tank, which is used to control its position and depth from the surface of the sea. A submarine submerges by letting water into the ballast tank so that its weight becomes greater than the buoyant force (and vice versa). It floats by reducing water in the ballast tank - thus its weight is less than the buoyant force.

14. A hot air balloon rises and floats due to the buoyant force (when the surrounding air is greater than the balloon’s weight). It descends when the balloon’s weight is more than the buoyant force. It becomes stationary when the weight equals the buoyant force. The weight of the hot-air balloon can be controlled by varying the quantity of hot air in the balloon.

16. Freshwater or saltwater? Air or water? Oil or water?

17. A hydrometer is an instrument to measure the relative density of liquids. It consists of a tube with a bulb at one end. Lead shots are placed in the bulb to weigh it down and enable the hydrometer to float vertically in the liquid. In a liquid of lesser density, a greater volume of liquid must be displaced for the buoyant force to equal to the weight of the hydrometer so it sinks lower. A hydrometer’s small floats higher in a liquid of higher density.

19. A CHANGE IN PRESSURE at any point in an enclosed fluid is transmitted EQUALLY and unchanged in all directions THROUGHOUT the fluid and to the walls of the container

20. When a small force or load is placed on the small piston (F 1 ), it acts through the liquid to the large piston to produce a very large force on F 2 that causes the load to rise a Shorter distance.

22. A hydraulic jack operates on Pascal’s Principle Can you see why it’s much easier to use a hydraulic jack to lift a car than by hand? http://www.edumedia-sciences.com/en/a260- hydraulic-lift

23. The hydraulic press is applied in our daily life: Hydraulic car jack. Hydraulic brakes.