Pressure and hydraulics

In short: Pressure is force per area (p = F / A), measured in pascal or bar. In liquids pressure spreads evenly in all directions: hydraulics makes use of this.

In more detail: The principle comes from Blaise Pascal.

In detail

• Units: 1 bar = 100,000 pascal; air pressure is about 1 bar (luftdruck-und-wetter).
• Tyre pressure: Given in bar (reifendruck-richtig-pruefen).
• Hydraulic press: A small force on a small area produces a large force on a large area.
• Examples: Car brakes, lifting platform, excavator.
• Hydrostatic pressure: Increases with water depth, about 1 bar per 10 metres.
• Divers: Pressure equalisation in the ears is important.
• Instruments: Manometers measure pressure.
• Everyday life: A knife cuts well because the force acts on a small area (auftrieb-und-archimedes).