density

• The formula to calculate density is D = m/V
• Density is the mass per unit volume.
• To find out if an object will float or sink, compare its density with that of water (1000 kgm-3). If it's less dense than water, it floats; if more dense, it sinks.
• the density of a substance is determined by the mass of the atoms it is made from and how closely these atoms are packed together
• density also depends on the state of a substance
• in solids the particles are packed close together
• in liquids the particles are free to move so the same mass takes up more space.
• in gases the particles take up a much greater volume than in liquids and solids
• for any particular substance, a solid is usually denser than its liquid and the liquid is usually denser than the gas
• solid water (ice) is less dense than liquid water. this is why ice floats on water