7TH GRADE · PRESSURE
Atmospheric pressure and hydraulics
Barometer, pressure gauge, pump and power gain of a hydraulic press.
The entire theory of the lesson is collected here; you can read it without an account. In interactive mode, the same theory appears as cards, followed by questions. with checking the answer and task, and progress is saved.
Basic Concepts
Atmospheric pressure
The pressure that atmospheric air exerts on bodies due to its weight and the movement of molecules.
With height, the column of air above the observer decreases, so the barometer reading usually becomes lower.
Experience with mercury column
The equilibrium of the liquid column and atmospheric pressure makes it possible to measure atmospheric pressure along the height of the column.
The barometer uses this principle directly or transmits pressure through the deformation of a sealed metal box.
Hydraulic machine
A device that transmits pressure through a liquid and gains strength due to the difference in the areas of the pistons.
A hydraulic press increases force, but the large piston travels just as much less distance in an ideal model.
Physical quantities
Force on small piston
Force applied to a piston with a smaller area.
Unit: newton ·
Power on the big piston
Force obtained on a larger piston area.
Unit: newton ·
Small piston area
Cross-sectional area of the small piston.
Unit: square meter ·
Large piston area
The cross-sectional area of a large piston.
Unit: square meter ·
Lesson formulas
Hydraulic machine
In an ideal machine, the pressures under both pistons are equal.
Tasks on the topic
Statements, answer options and the walkthrough.