Pressure

key notes:

Definition of Pressure:

• Pressure is a force applied per unit area.
• Mathematically, pressure (P) is defined as P = Force (F) / Area (A).

Units of Pressure:

• The SI unit of pressure is the Pascal (Pa), which is equal to one Newton per square meter (1 N/m²).
• Other common units of pressure include atmospheres (atm), millimeters of mercury (mmHg), and pounds per square inch (psi).

Factors Affecting Pressure:

1. Force: An increase in force applied to a given area will result in an increase in pressure.
2. Area: Decreasing the area over which a force is applied will increase the pressure, while increasing the area will decrease the pressure.

Pressure in Fluids:

• Liquids and gases are both considered fluids.
• Pressure in a fluid is transmitted equally in all directions (Pascal’s principle).

Hydraulic Systems:

• Hydraulic systems use the principle of transmitting force through a fluid to accomplish various tasks.
• These systems are commonly used in machines, like car brakes and hydraulic lifts.

Atmospheric Pressure:

• Atmospheric pressure is the pressure exerted by the weight of the Earth’s atmosphere on objects at or near the Earth’s surface.
• The standard atmospheric pressure at sea level is about 101.3 kPa.

Measuring Pressure:

• Common devices used to measure pressure include barometers (for atmospheric pressure) and manometers (for fluid pressure).

Applications of Pressure:

• Pressure is used in various applications, such as in scuba diving, weather forecasting, and the functioning of everyday items like tires and spray bottles.

Effects of Pressure on Matter:

• Pressure can change the state of matter. For example, increasing the pressure can turn a gas into a liquid (compression) or a liquid into a solid (freezing).

Pressure and Human Health:

• Changes in pressure can affect the human body, which is why decompression sickness (the bends) can occur in scuba diving at great depths.

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