IP Physics Notes (Upper Secondary, Year 3-4): 5) Pressure

Study guide30 Sep 2025, 00:00 ZUpdated 30 Nov 2025

Force-per-area basics, liquid columns, hydraulic systems, and Boyle's law for IP Y3-Y4 applied pressure questions.

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Q: What does IP Physics Notes (Upper Secondary, Year 3-4): 5) Pressure cover?
A: Force-per-area basics, liquid columns, hydraulic systems, and Boyle's law for IP Y3-Y4 applied pressure questions.

Quick recap -- Pressure concentrates force over area. In fluids it scales with depth, density, and gravity; in gas systems it trades off with volume when temperature stays fixed.

The core idea is simple: Pressure is force spread over area.

Use it as a working check: Smaller area gives higher pressure for the same force. In liquids, pressure increases with depth, density, and gravity. In sealed gases, pressure and volume trade off at constant temperature.

Then go one layer deeper: Use the pool wall and hydraulic jack examples to practise choosing between $P = F/A$ , $P = \rho gh$ , Pascal's principle, and Boyle's law.

Keep your practice loop tight via our IP Physics tuition hub-it links each topic here to quizzes, diagnostics, and WA-style problem sets.

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Reviewed by

Chee Wei Jie·Academic Advisor (Physics)

Question cue	Start with	Check before calculating
A force acts on a stated contact area	$P = \frac{F}{A}$	Use the force perpendicular to the surface and convert area to $\pu{m2}$ .
A point is deeper in a liquid	$P = \rho g h$	Use vertical depth below the surface, not slanted distance or container width.
Two pistons are linked by trapped liquid	$\frac{F_1}{A_1} = \frac{F_2}{A_2}$
A U-tube column height is different on two sides	$\Delta P = \rho g \Delta h$	Decide whether the question wants gauge pressure or comparison with atmospheric pressure.
A sealed gas changes volume at constant temperature	$P_1V_1 = P_2V_2$

Scenario	Contact area	Applied force	Resulting pressure
Drawing pin point	Very small	Thumb force	Very high -- tip bites into board
Snowshoe	Wide	Body weight	Low -- spreads load so you do not sink
Knife edge	Sharpened	Cutting push	High -- blade slices material

Question clue	First check	Calculation move	Common trap
Area is given in $\pu{cm2}$ or $\pu{mm2}$	Pressure in pascals needs $\pu{m2}$ .	Convert area before division.	Treating $\pu{4.0 cm2}$ as $\pu{4.0 m2}$ .
A slanted push acts on a surface	Only the perpendicular component produces pressure on that surface.	Use the normal component of the force.	Using the full angled force without resolving.
A shoe, snowshoe, tyre, or support has a wider base	Compare cases with the same weight first.	Larger area gives lower pressure when force is unchanged.	Saying "larger area always lowers pressure" even when the force also changes.
A sharp point or blade is used	Contact area is deliberately tiny.	Same force over smaller area gives higher pressure.	Saying sharp objects work because they use a bigger force.

Question clue	What to check first	Setup move	Common trap
"Fixed mass of gas" or "sealed syringe"	The same gas particles stay inside.	Use $P_1V_1=P_2V_2$ .	Applying Boyle's law when gas is leaking or being added.
"Temperature remains constant"	Average kinetic energy is unchanged.	Pressure changes only because volume changes.	Using Boyle's law during heating or cooling without checking temperature.
Volume is halved	Smaller volume means more frequent wall collisions.	Pressure doubles if the gas mass and temperature stay fixed.	Saying pressure halves because volume halves.
Mixed units such as $\pu{cm3}$ and $\pu{m3}$	Both volumes must use the same unit.	Convert before substituting, or keep both volumes in $\pu{cm3}$

IP Physics Notes (Upper Secondary, Year 3-4): 5) Pressure

Formula Choice Checkpoint

Defining Pressure

Pressure in Solids: Force vs Area

Contact-area pressure checkpoint

Hydrostatic Pressure

Worked Example: Swimming Pool Wall

Pascal's Principle & Hydraulic Systems

Worked Example: Service Garage Jack

Measuring Pressure

Manometer direction checkpoint

Gas Pressure & Boyle's Law

Boyle's law setup checkpoint

Practice Quiz

Key Takeaways

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