1. Unit 1 Lesson 5 Fluids and Pressure
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2. Feel the Pressure! 1. What are fluids?
Unit 1 Lesson 5 Fluids and Pressure
Feel the Pressure!
1. What are fluids?
A fluid is any material that can flow and that takes the shape of its container.
A fluid can flow because its particles easily move past each other.
Liquids and gases, including water and air, are fluids.
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3. 2. Why do fluids exert pressure?
Unit 1 Lesson 5 Fluids and Pressure
2. Why do fluids exert pressure?
Pressure is the measure of how much force is acting on a given area.
All fluids exert pressure.
Fluids are made of tiny particles that are constantly moving.
The particles in fluids bump against one another and against the walls of their container, creating pressure.
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4. Why do fluids exert pressure?
Unit 1 Lesson 5 Fluids and Pressure
Why do fluids exert pressure?
Why does the air in a balloon exert pressure on the balloon?
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5. 3. How is pressure calculated?
Unit 1 Lesson 5 Fluids and Pressure
3. How is pressure calculated?
Pressure equals force divided by area.
The unit for pressure is the pascal.
1 Pa = 1 N/m2
(One pascal equals the force of one newton exerted over an area of one square meter.)
A greater force results in GREATER pressure.
A greater area results in less pressure.
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6. Under Pressure What are two familiar fluids that exert pressure?
Unit 1 Lesson 5 Fluids and Pressure
Under Pressure
What are two familiar fluids that exert pressure?
The pressure caused by the weight of the atmosphere is called atmospheric pressure.
The pressure caused by the weight of water is called water pressure.
The TOTAL pressure under water is the sum of the pressures of the atmosphere and the water above.
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7. How does depth affect fluid pressure?
Unit 1 Lesson 5 Fluids and Pressure
How does depth affect fluid pressure?
As an object travels deeper into the atmosphere, the atmospheric pressure increases.
Water pressure also increases as depth increases.
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8. Unit 1 Lesson 5 Fluids and Pressure
Thar She Blows!
What are some examples of fluid motion due to pressure?
All fluids flow from areas of HIGHER PRESSURE to areas of lower pressure.
EXAMPLES OF FLUID MOTION:
Wind
Leaks in a Balloon or tire
Breathing
Leak in a hose or pipe
A dam
A geyser, i.e. Old Faithful
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9. Sink or Swim? What causes buoyant force?
Unit 1 Lesson 5 Fluids and Pressure
Sink or Swim?
What causes buoyant force?
Buoyant force is an upward force that fluids exert on all matter.
When an object is immersed in fluid, the fluid pushes against the object with an upward, or buoyant, force.
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10. How is buoyant force calculated?
Unit 1 Lesson 5 Fluids and Pressure
How is buoyant force calculated?
Buoyant force = the weight of fluid that is displaced.
This is known as Archimedes’ principle, named for a Greek mathematician who lived in the third century B.C.E.
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11. What can happen as a result of weight and buoyant force?
Unit 1 Lesson 5 Fluids and Pressure
What can happen as a result of weight and buoyant force?
FLOAT: if the object’s weight is equal to the buoyant force, this is called neutral buoyancy.
SINK: if the object’s weight is greater than the buoyant force.
BUOYED UP: If the object’s weight is less than the buoyant force.
The object moves upward in the fluid until the buoyant force equals the object’s weight. When this happens, the object floats.
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12. What can happen as a result of weight and buoyant force?
Unit 1 Lesson 5 Fluids and Pressure
What can happen as a result of weight and buoyant force?
Will these objects float, sink, or be buoyed up when submerged in water?
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13. What affects the density of an object?
Unit 1 Lesson 5 Fluids and Pressure
What affects the density of an object?
The density of an object equals its mass divided by its volume.
D = m/v
When density increases, objects sink.
When density decreases, objects float or buoy up.
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14. What affects the density of an object?
Unit 1 Lesson 5 Fluids and Pressure
What affects the density of an object?
EXAMPLE: A submarine sinks and rises by filling or emptying its ballast tanks. This process changes its density.
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15. What affects the density of an object?
Unit 1 Lesson 5 Fluids and Pressure
What affects the density of an object?
EXAMPLE: Ships float on water because they are built with a hollow shape to hold more air. This decreases its density.
EXAMPLE: Most bony fish have an organ called a swim bladder. This organ is filled with gases. By adjusting the volume of gas in its swim bladder, the fish can move to different depths of water.
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