How Pressure Is Calculated (P = F/A)
Pressure is defined as force applied per unit area. The same force spread over a larger area produces lower pressure; concentrated on a smaller area, it produces higher pressure. This is why sharp knife edges cut easily (small area = high pressure) and snowshoes keep you from sinking (large area = low pressure). Pressure is fundamental to hydraulics, pneumatics, weather systems, and medicine.
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Formula
Pressure Calculator
Calculate pressure, force, or area using P = F/A.
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Worked Example
Given:
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FAQs
What are common pressure units?
Pascal (Pa) is the SI unit: 1 N/m². Other units include kilopascal (kPa = 1,000 Pa), bar (100,000 Pa), PSI (pounds per square inch, 6,895 Pa), atmosphere (atm = 101,325 Pa), and mmHg (Torr = 133.3 Pa). Atmospheric pressure at sea level is 101,325 Pa ≈ 1 atm ≈ 14.7 PSI.
How does a hydraulic system multiply force?
Pascal's law states that pressure in an enclosed fluid transmits equally in all directions. A small force on a small piston creates pressure P = F₁/A₁. This same pressure on a larger piston produces force F₂ = P × A₂, where A₂ >> A₁. Car brakes, hydraulic lifts, and excavators use this principle.
Why does pressure increase with depth in water?
Water above exerts weight, and pressure = weight/area = ρgh, where ρ is fluid density, g is gravity, and h is depth. For every 10 m of water depth, pressure increases by approximately 1 atm. At 10 m depth, pressure is 2 atm; at 100 m, about 11 atm. This is why deep-sea equipment needs thick pressure hulls.