Subject: Science, Physics, not General Physics. Topic: Pressure. Would you mind helping me answer these end of chapter questions? Please don't answer number 12 on a Pink box. Thank you for your help. If you can't find the answer, just research and get the references to pressure. (Pressure on a surface, Reducing pressure, Increasing pressure, Particles and pressure, Pressure in liquids, Pressure and depth of a liquid, Hydraulic equipment, Pressure of Gases: Pressure of the atmosphere, Ear popping, Hoe a sucker sticks, Crushing a can, Aerosols, Hovercraft)

O PHYSICS The cushion of air beneath the hovercraft reduces friction between it and the ground. The cushion of air is also maintained when the hovercraft moves over water. The forward or backward thrust on the hovercraft is provided by propellers in the air above the hovercraft. propeller air fan flexible skirt 12 What are the advantages of using a hovercraft as a means of transport? Figure 14.18 Hovercrafts work by riding on a cushion of air above the ground or water surface. SUMMARY Pressure acts when a force acts over an area of surface (see page 176). When a solid object exerts a pressure on the surface below it, the smaller the area of contact, the greater the pressure (see page 177). Pressure in a liquid acts in all directions and increases with the depth of the liquid (see page 181). In hydraulic systems pressure is transmitted through a liquid (see page 182) The atmosphere exerts a pressure (see page 183). Use is made of the pressure of air in various devices such as suckers, pumps and hovercraft. Use is made of the pressure of other gases in aerosols (see pages 184-188). End of chapter question How could you explain the following, using the model of air made up of particles which move freely? a) How air pushes on a surface. b) Why the pressure in an Inflated tyre is higher than the air pressure outside. c) Why a sucker stays in place on a flat surface. 188