====== Pressure ======
18. Pressure + force ÷ area
19.The correct units of pressure are N/m2 or N/cm2.
20.There is only one formula you need in pneumatics - that for calculating the force output from a cylinder. You will be given the formula sheet at the front of your GCSE answer book. So all you have to do is make sure you know how to use it! The force you get out of a cylinder depends on the air pressure inside it, and the size or area of the piston. The formula is: Force (F) = pressure (p) × area (a)
21.I can describe an experiment to show that pressure in liquids increases with depth
22.Liquids are made up of very small particles, when you go deeper into the water the density builds because the number of particles builds up above you. These particles are constantly moving around in rapid motion and they slide past each other, this is why a liquid is constantly rippling. E.G. When water is placed into a glass with three holes in it and there is one above each other. The hole in the bottom will have the most water force coming out of it because there are more particles forcing their way to get out of the glass and the density at the bottom is more high because there are more particles in that area.
23.Liquids are used in a hydraulics system because:
24.The particles in a liquid are packed closely together and are incompressible.
25.I can use the pressure formula to calculate pressures, forces or areas in hydraulic systems. The formula is P=F/A, pressure=force ÷ area, force=pressure × area or area= force × pressure
26.The particles in a gas move quickly in all directions. When gas particles hit the walls of their container they cause pressure. The pressure rises as more and more particles hit the walls of the container.
28. Imagine that a force of 10 N acted on a see-saw 2 m from the pivot. This is how we would work out the moment: Force × distance = moment 10 × 2 = 20 Nm
29.When we measure moments, we use the units Ncm or Nm.
30.Moments can be either clockwise or anticlockwise. If a moment is clockwise it will lean to the right as it will have more pressure on the right. If a moment it anticlockwise it will lean to the left as it will have more pressure on the left.
32.If the moment is unbalanced, the lever will move. The resultant is which direction it will move in.
33.• If the moments are equal and opposite they will cancel. • You must ensure that the total force on each side is the same. • The clockwise moment must be equal to the anticlockwise moment.