Pressure = Force ÷ Area. When you press a drawing pin into a board, the sharp point creates high pressure because the same force is concentrated on a tiny area. This is why pins pierce easily but your finger pressing with the same force cannot
💡Key Properties
Pressure is directly proportional to force and inversely proportional to area. Double the force, double the pressure. Double the area, halve the pressure. Pressure acts in all directions in fluids (Pascal's Law).
At any point in a stationary fluid, pressure is the same in all directions.
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Formula Block
Memorise — at least one formula appears in every paper
Pressure (P) = Force (F) ÷ Area (A)
Fluid Pressure = Density × g × Height
Atmospheric Pressure = 1.013 × 10^5 Pa = 760 mm Hg
Units: Pascal (Pa), N/m², Bar, Atmosphere, mm Hg
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Exam Patterns
What examiners ask — read before attempting PYQs
SSC asks about atmospheric pressure values, pressure applications (hydraulic systems, barometers), and calculation problems. Questions often involve pressure differences at heights, pressure in liquids, and practical applications like syringes, pumps.
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Shortcuts
Use these to save 30–60 seconds per question
Remember 'FAPA' - Force and Area are in Pressure Always. Increase Force = Increase Pressure. Increase Area = Decrease Pressure.
For fluid pressure, remember 'DGH' - Density × Gravity × Height.
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Worked Example
Solve this step-by-step before moving on
1
Step 1
Identify given values - Force = 200 N, Area = 4 m²
2
Step 2
Apply formula - Pressure = Force ÷ Area
3
Step 3
Substitute values - Pressure = 200 ÷ 4
4
Step 4
Calculate - Pressure = 50 N/m² or 50 Pa
Another Example: If the same 200 N force acts on 2 m² area instead:
Pressure = 200 ÷ 2 = 100 Pa
Notice: Half the area means double the pressure.
Shortcut for Unit Conversion: 1 Bar = 10^5 Pa. For quick conversion, Bar to Pa - add 5 zeros. Pa to Bar - remove 5 zeros.
Common Mistakes: Students often confuse force with pressure. Remember - force is push or pull, pressure is force per unit area. Another mistake is forgetting that liquid pressure depends on depth (height of liquid column), not the total volume. A thin tube and wide tank at same depth have equal pressure at bottom.
Practical Applications tested: Hydraulic brakes work on Pascal's law. Barometers measure atmospheric pressure. Syringes work due to pressure difference. Mountain climbers face low pressure at heights. Deep sea divers face high pressure underwater.
🔑 Key Points
Pressure = Force ÷ Area - fundamental formula for all pressure calculations
Atmospheric pressure at sea level = 1.013 × 10^5 Pa = 760 mm Hg
Liquid pressure = Density × g × Height, independent of container shape
Pascal's Law: Pressure applied to confined fluid transmits equally in all directions
High pressure created by small area (needle, knife) for cutting applications
Pressure decreases with altitude - 1% decrease per 80m height gain
Barometer measures atmospheric pressure using mercury column height
Hydraulic systems multiply force using pressure and area relationship
📌 Exam Facts
Standard atmospheric pressure = 1.013 × 10^5 Pascal = 1.013 Bar
Mercury barometer reading at sea level = 760 mm Hg = 76 cm Hg
Pressure unit Pascal named after French scientist Blaise Pascal
1 Bar = 10^5 Pascal = 0.987 atmosphere approximately
Density of mercury = 13,600 kg/m³ used in barometer calculations
Blood pressure measured in mm Hg using sphygmomanometer
Pressure at 10m underwater depth = 2 atmospheric pressure
Hydraulic jack multiplies force based on area ratio principle
🚀 60-Second Revision
Formula: Pressure = Force ÷ Area, units Pascal or N/m²
Remember: 1 atm = 1.013 × 10^5 Pa = 760 mm Hg
Liquid pressure depends only on depth, not container shape or volume
Pascal's Law: Pressure transmits equally in all directions in fluids
Applications: Hydraulic brakes, barometers, syringes all use pressure principles
Trap: Don't confuse force with pressure - pressure is force per unit area
Quick conversion: 1 Bar = 10^5 Pa (add/remove 5 zeros)
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Test yourself under real exam conditions
A timed SBI PO mock shows exactly how Physics — Everyday Concepts questions appear in the actual paper — and where you lose marks.