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< BackNext >PreviewMain Chapter 14 Forces in Fluids Preview Section 1 Fluids and PressureFluids and Pressure Section 2 Buoyancy and DensityBuoyancy and.

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Presentation on theme: "< BackNext >PreviewMain Chapter 14 Forces in Fluids Preview Section 1 Fluids and PressureFluids and Pressure Section 2 Buoyancy and DensityBuoyancy and."— Presentation transcript:

1 < BackNext >PreviewMain Chapter 14 Forces in Fluids Preview Section 1 Fluids and PressureFluids and Pressure Section 2 Buoyancy and DensityBuoyancy and Density Concept Map

2 < BackNext >PreviewMain Section 1 Fluids and Pressure Chapter 14 Fluids and Pressure A fluid is a nonsolid state of matter in which the atoms or molecules are free to move past each other. A fluid is any material that can flow and that takes the shape of its container. Liquids and gases are fluids.

3 < BackNext >PreviewMain Section 1 Fluids and Pressure Chapter 14 Fluids and Pressure, continued Pressure is the amount of force exerted on a given area. Moving particles of matter create pressure by colliding with one another and with the walls of their container. Fluids exert pressure evenly in all directions.

4 < BackNext >PreviewMain Section 1 Fluids and Pressure Chapter 14 Fluids and Pressure, continued Any force, such as the weight of an object, acting on an area creates pressure. The SI unit for pressure is the pascal. One pascal (1 Pa) is the force of one newton exerted over an area of one square meter (1 N/m 2 ).

5 < BackNext >PreviewMain Section 1 Fluids and Pressure Chapter 14 Atmospheric Pressure The atmosphere is the layer of nitrogen, oxygen, and other gases that surrounds Earth. The pressure caused by the weight of the atmosphere is called atmospheric pressure.

6 < BackNext >PreviewMain Section 1 Fluids and Pressure Chapter 14 Atmospheric Pressure, continued The atmosphere extends about 150 km above Earth’s surface. Atmospheric pressure changes as you travel through the atmosphere. At the top of the atmosphere, pressure is almost nonexistent because there are fewer gas particles and they rarely collide.

7 < BackNext >PreviewMain Forces in Fluids Chapter 14 Atmospheric Pressure

8 < BackNext >PreviewMain Section 1 Fluids and Pressure Chapter 14 Water Pressure Water is a fluid. So, like the atmosphere, water exerts pressure. Water pressure increases as the depth of the water increases. Water pressure depends on depth, not on the total amount of fluid present.

9 < BackNext >PreviewMain Section 1 Fluids and Pressure Chapter 14 Water Pressure, continued A person swimming 3 m below the surface of a small pond feels the same pressure as a person swimming 3 m below the surface of a large lake. Because water is about 1,000 times denser than air, water exerts more pressure than air does.

10 < BackNext >PreviewMain Section 1 Fluids and Pressure Chapter 14 Pressure Differences and Fluid Flow Fluids flow from areas of high pressure to areas of low pressure. Differences in air pressure help explain the way your body breathes and the way tornadoes create damaging winds.

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12 < BackNext >PreviewMain Section 2 Buoyancy and Density Chapter 14 Buoyant Force and Fluid Pressure All fluids exert an upward force called buoyant force. Buoyant force is the upward force that keeps an object immersed in or floating on a liquid. Buoyant force is caused by differences in fluid pressure.

13 < BackNext >PreviewMain Forces in Fluids Chapter 14 Buoyant Force

14 < BackNext >PreviewMain Section 2 Buoyancy and Density Chapter 14 Buoyant Force and Fluid Pressure, continued A Greek mathematician named Archimedes discovered how to find buoyant force. Archimedes’ principle states that the buoyant force on an object in a fluid is an upward force equal to the weight of the volume of fluid that the object displaces.

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16 < BackNext >PreviewMain Section 2 Buoyancy and Density Chapter 14 Weight Versus Buoyant Force An object in a fluid will sink if the object’s weight is greater than the buoyant force (the weight of the fluid that the object displaces). An object floats only when the buoyant force on the object is equal to the object’s weight.

17 < BackNext >PreviewMain Forces in Fluids Chapter 14 Buoyant Force on Floating Objects

18 < BackNext >PreviewMain Section 2 Buoyancy and Density Chapter 14 Density and Floating Density is mass per unit volume. Any object that is denser than the surrounding fluid will sink. An object that is less dense than the surrounding fluid will float.

19 < BackNext >PreviewMain Section 2 Buoyancy and Density Chapter 14 Determining Density To determine the density of an object, you need to know the object’s mass and volume. A balance can be used to find the mass of an object. To find the volume of a regular solid, such as a cube, multiply the lengths of the three sides together.

20 < BackNext >PreviewMain Section 2 Buoyancy and Density Chapter 14 Determining Density, continued To find the volume of an irregular solid, use water displacement. By measuring the volume of water that the object displaces, or pushes aside, you find the volume of the object itself.

21 < BackNext >PreviewMain Section 2 Buoyancy and Density Chapter 14 Changing Overall Density The overall density of an object can be changed by changing the object’s shape, mass, or volume. Submarines use ballast tanks to change their overall density and dive under water. As water is added to the tanks, the submarine’s mass increases, but its volume stays the same.

22 < BackNext >PreviewMain Section 2 Buoyancy and Density Chapter 14 Changing Overall Density, continued Most bony fishes have an organ called a swim bladder that allows them to adjust their overall density. An inflated swim bladder increases the fish’s volume, which decreases the fish’s overall density so the fish does not sink.

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