Pressure Flashcards
(25 cards)
What is a fluid?
Any substance that can flow.
What does the term fluid apply to?
Both liquids and gases.
What is pressure?
The perpendicular force per unit area acting on a surface.
What is the formula for pressure?
P = F/A.
What is the SI unit of pressure?
Newtons per square metre (Nm⁻²).
What is another unit of pressure?
Pascal (Pa).
What is the relationship between Pascal and Newtons per square meter?
1 Pa = 1 Nm⁻².
What is another unit of pressure?
Bar.
What is the relationship between bar
Nm⁻²
Is pressure a scalar or vector quantity?
Scalar quantity.
Does pressure have direction?
No.
What is Pascal’s principle?
The pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and the walls of the containing vessel.
What is a hydraulic press?
A device that uses Pascal’s principle to multiply force.
What is the formula for pressure in a fluid?
p = hρg
How does pressure in a liquid change with depth?
Increases in direct proportion to the depth of the liquid.
How does pressure in a liquid change with density?
Varies directly with density.
What is atmospheric pressure?
The pressure exerted by the atmosphere on the surface of the earth.
Approximately what is the atmospheric pressure at sea level?
About 10⁵ Pa.
What is a barometer?
An instrument used to measure atmospheric pressure.
What is a manometer?
An instrument used to measure gas pressure.
What is a siphon?
A device used to remove liquids from receptacles which cannot be lifted or easily reached.
What is a syringe?
A device with a piston that is used to eject liquid.
What is a pump?
A device that can produce a pressure difference.
What is relative density?
The ratio of the density of a substance to the density of a reference substance (usually water).
