What is pressure?
Pressure is the perpendicular force per unit area acting on a surface.
What is the SI unit of pressure?
Newton per square meter (N/m²) or Pascal (Pa).
State the formula for pressure.
$$ P = \frac{F}{A} $$
What happens to pressure if the area decreases while force stays constant?
Pressure increases.
What happens to total force if a small pressure is applied over a large area?
A large total force is produced.
What are the factors that affect pressure in liquids?
Depth, density of the liquid, and gravitational acceleration.
Write the formula for pressure in a liquid.
$$ P = h \rho g $$
What does the symbol ρ represent in the formula \( P = hρg \)?
Density of the liquid (kg/m³).
How does pressure change with depth in a liquid?
Pressure increases as depth increases.
What is Pascal's Principle?
Pressure applied to an enclosed fluid is transmitted equally and undiminished in all directions.
Give one application of Pascal’s Principle.
Hydraulic systems such as car brakes or hydraulic presses.
What is a pressure gauge used for?
To measure and display pressure in gases or liquids.
What is another name for a pressure gauge?
A vacuum gauge.
What is a barometer used to measure?
Atmospheric pressure.
Who invented the mercury barometer?
Evangelista Torricelli in 1643.
What liquid is used in a simple barometer and why?
Mercury, because it is dense and reduces the size of the instrument.
What is inside the metal capsule of an aneroid barometer?
An aneroid capsule made of beryllium-copper alloy.
How does an aneroid barometer work?
Atmospheric pressure causes the capsule to expand or contract, moving levers and springs that indicate pressure.
What is a manometer used for?
To measure pressure in liquids or gases.
What does an open manometer measure?
Gas pressure relative to atmospheric pressure.
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