Pressure

Notes

What you need to know

• Define pressure as force per unit area: P = F/A
• Recall and use P = F/A; convert area units between cm² and m²
• Explain everyday examples of high and low pressure in terms of force and contact area
• State that pressure in a liquid increases with depth and depends on the density of the liquid
• State that pressure at a given depth in a liquid acts equally in all directions
• Recall and use P = hρg to calculate pressure, depth, or density in a liquid
• Describe how atmospheric pressure arises from the weight of air above, and decreases with altitude
• Describe how a mercury barometer works and how the height of mercury indicates atmospheric pressure
• Use h = P/(ρg) to relate atmospheric pressure to the height of a mercury column
• Describe and use a U-tube manometer to compare or measure gas pressure

Syllabus subtopics

• Pressure definition and equation
• Pressure in liquids