Core ConceptRead this first — the foundation of the topic
Pressure is a fundamental physics concept that appears regularly in SSC CGL exams. It measures how much force is applied per unit area. Think of it as 'force concentration' - the same force spread over a smaller area creates higher pressure. Core Concept: 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 RulesCore rules you must know cold
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.
Formula BlockMemorise — 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
Exam PatternsWhat 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.
ShortcutsUse 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.
Worked ExampleSolve 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.
Exam TrapsCommon mistakes students make — avoid these
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 to Remember
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-Specific Tips
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
Practice MCQs
Physics — Everyday Concepts — Practice Questions
41graded MCQs · easy to hard · full solution & trap analysis · showing 20 of 41
What is the speed of light in vacuum according to modern physics?
Practice 2easy
Which physicist formulated the law of universal gravitation?
Practice 3easy
Which scientist formulated the law of universal gravitation?
Practice 4easy
Which scientist is credited with the invention of the electric light bulb?
Practice 5easy
Which physical quantity is measured in Hertz (Hz)?
Practice 6easy
What is the SI unit of temperature?
Practice 7easy
What is the SI unit of energy?
Practice 8easy
Which of the following statements about friction is correct?
Practice 9easy
What is the SI unit of force?
Practice 10easy
Which of the following is the SI unit of electric current?
Practice 11easy
What is the SI unit of force?
Practice 12easy
Which of the following is an example of a renewable source of energy?
Practice 13medium
Which of the following statements about pressure is correct?
Practice 14medium
Which of the following is the SI unit of electric current?
Practice 15medium
A person uses a concave mirror to shave or apply makeup because concave mirrors produce:
Practice 16medium
When light passes from a denser medium (like glass with refractive index 1.5) to a less dense medium (like air with refractive index 1.0), the light ray bends:
Practice 17medium
A sound wave travels through air at approximately 340 m/s at room temperature (20°C). If a person hears an echo 2 seconds after shouting, what is the approximate distance to the reflecting surface (wall/cliff)?
Practice 18medium
Which of the following phenomena best explains why a person feels lighter when standing in an elevator moving downward with acceleration?
Practice 19medium
Which of the following best describes the phenomenon of refraction of light?
Practice 20medium
What is the relationship between frequency and wavelength of a wave in the same medium?
21 more practice questions in the Study Panel
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