Unit 1: Solids, Liquids and GasesDensitySolids are often very dense, liquids are less dense than solids, and gases have very low densities. Density is how much mass something has for a certain volume in other words, how squashed up something is.To calculate density, use this equation:Density = Mass / VolumeExample: A piece of iron has a mass of 390kg and a volume of 0.05m3. What is its density?P = 390 kg/0.05m3P = 7800 kg/m3 ? Density can be kg/m3, g/cm3 etc...Calculating Volumes for the DensityTo find the volume of irregular solids, measure out a certain amount of water with a measuring cylinder. This is the control (something to compare results to). Do the same with another measuring cylinder, and drop the solid in. Note the rise in the level of water. The difference between the two measurements is the volume of the solid, in this case, 10ml.PressurePressure in SolidsPressure is defined as the force per unit area. Force is measured in newtons (N) and area is measured in square metres (m2). The unit for pressure is N/m2 or Pa (for Pascals).There is an equation that comes with pressure and this is only for solids:Pressure = Force / AreaExample: A woman weighs 600N and the total area of her shoes in contact with the ground is 0.0015m2. Find the pressure she is exerting to the ground.p = 600N/0.0015m2p = 400000PaPressure in Liquids and GasesPressure in liquids acts equally in all directions as long as the liquid is not moving.