Zusammenfassung der Ressource
Pressure And Moments
- Pressure
- Pressure is the effect of a force acting on an area. Pressure can be increased either by increasing the force or by decreasing the area.
- Pressure can be calculated from the formula:
- pressure=force (divided by) area
- The SI unit of pressure is the newton per square metre (N/m2). This unit is called the pascal (Pa).
- 1N/m2 = 1Pa
- Gas
- Gas pressure is produced by gas molecules colliding with the container walls, and with anything in the gas.
- A gas is compressible. It can be squeezed into a smaller volume by increasing the pressure in it.
- Pneumatic describes the action of machines that use gas pressure to work.
- Liquid
- A liquid is incompressible, it cannot be squeezed into a smaller volume.
- Applied pressure is transmitted throughout a liquid or a gas inside a container.
- Hydraulic describes the action of machines
that use liquid pressure to work.
- Pressure increases with dept. This is
because the weight of the liquid or
gas overhead increases with depth.
- Moments
- The turning effect of a force is called a moment.
- The moment of a force can be increased either by increasing the force, or
by increasing the distance of the force from the turning point (pivot).
- The moment of a force can be calculated from the formula:
- moment= force x distance of force from pivot
- The principle of moments states that an object is balanced
when clockwise and anticlockwise turning moments are equal.
- A lever uses the principle of moments to amplify the force, or the distance moved, when an effort is used to move a load.