13.1 Fluid Pressure
Reading Focus
Key Concepts
How is pressure calculated?- How does water pressure change with depth?
- How is pressure distributed at a given level in a fluid?
- How does air pressure change with altitude?
Vocabulary
pressure
pascal
fluid
Reading Strategy
Using Prior Knowledge Before reading the? section, copy the table below. In it, write the common definition of the word pressure. After you have read the section, write the scientific definition of pressure and contrast it to your original definition.
Meanings of Pressure |
|
|---|---|
Common definition |
a. |
Scientific definition |
b. |
Why is a theater seat so much more comfortable than a bicycle seat? One of the main reasons any seat is comfortable is the pressure it exerts on your body. As you read this chapter, you'll learn about pressure, and how fluids such as air and water can exert and transmit pressure.
Pressure
The comfort of the plush theater seats shown in Figure 1 is related to pressure—the result of a force distributed over an area. A theater seat's large padded seat and back offer a larger area to support your weight than a bicycle seat does. Thus, the theater seat exerts less pressure on you and is more comfortable than the bicycle seat.
Many other everyday situations also involve pressure. A sharp pencil easily pokes a hole through a sheet of paper, whereas the eraser end of the pencil does not. Why is this? The reason is the same—pressure.
Figure 1 Because the theater? seat exerts a supporting force over a larger area, it is more comforta ble than the bicycle seat. Comparing and Contrasting What force acts on both seats?
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