PRESSURE

PRESSURE

1. pressure

   • formula
   • unit
     • pascal or Nm^2
   • applications
     • high pressure
       • a sharp knife has a very small surface area on its cutting edge so that high pressure can be exerted to cut the meat
       • nails needles and pins have very sharp ends with very small surface areas when a force is applied on the head of a nail pressure will drive its sharp end into a piece of wood easily
       • the studs on a Football boot have a small amount area of contact with the ground the pressure under the studs is high enough for them to sink into the ground which gives extra grip
     • low pressure
       • skis have a large area to reduce the pressure on the snow so that they do not sink in to far
       • a tractor moving on soft ground has wide Tyres to reduce the pressure on the ground so that they will not sink into the ground
       • a wide shoulder pad of a heavy bag will reduce the pressure exerted on the shoulder of the person carrying the bag

2. ARCHIMEDES' PRINCIPLE

   • formula
     • wt.of object÷ wt. of displaced fluid = density of object ÷density of fluid
   • applications
     • 1. Submarine: A submarine has a large ballast tank, which is used to control its position and depth from the surface of the sea. A submarine submerges by letting water into the ballast tank so that its weight becomes greater than the buoyant force. Conversely, it floats by reducing water in the ballast tank.-thus its weight is less than the buoyant force

3. LIQUID PRESSURE

   • formula
     • h×density×g
   • characteristics
     • Unlike a solid, the molecules in a liquid have a much greater freedom to move. ... A liquid, like a gas, displays the properties of a fluid. A liquid can flow, assume the shape of a container, and, if placed in a sealed container, will distribute applied pressure evenly to every surface in the container.

4. GAS PRESSURE

   • atmospheric pressure
     • measuring
       • simple barometer
       • fortins barometer
       • anaroid barometer
   • measurment
     • manometer

Images and files in the map