P3: Changes of State & the Particle Model Physics GCSE

• What is density defined as?

  The mass per unit volume of a material
• How does the density of low density materials compare to their mass?

  They typically have a low mass
• How does the mass of similarly sized objects differ based on density?

  High density objects have a high mass
• Which is lighter: a bag of feathers or a bag of metal?

  A bag full of feathers
• Why is a balloon less dense than a small bar of lead?

  Because the balloon occupies a larger volume
• What is the relationship between density, mass, and volume?

  Density = mass/volume
• Why are gases less dense than solids?

  Molecules in gases are more spread out
• What happens to objects denser than water?

  They will sink
• How can the volume of an object be calculated?

  Using the appropriate equation for its shape
• How do you calculate the volume of the paving slab?

  Volume = 0.04 × 0.5 × 0.85
• What is the density of the paving slab calculated as?

  4294 kg/m³
• What is the rounded density of the paving slab to two significant figures?

  4300 kg/m³
• What are the tips for converting between units?

  • Multiply when converting larger to smaller units
  • Divide when converting smaller to larger units
• How is mass defined?

  Amount of matter in a substance
• How is weight defined?

  Force acting on an object in gravity
• How is density defined in terms of mass and volume?

  Amount of matter in a fixed volume
• How can density be visualized at the atomic level?

  By considering particles in a cubic centimetre
• Why is liquid water denser than steam?

  Liquid water contains more particles in 1 cm³
• What are the characteristics of solids, liquids, and gases?

  • Solids: Fixed shape and volume, particles closely packed
  • Liquids: No fixed shape, definite volume, particles can flow
  • Gases: No fixed shape or volume, particles far apart
• How do particles behave in solids?

  They vibrate about fixed positions
• How do particles behave in liquids?

  They can flow over one another
• How do particles behave in gases?

  They move randomly and are far apart
• Why are gases highly compressible?

  There are large gaps between the particles
• What is the difference in density between solids, liquids, and gases?

  • Solids and liquids: High density, tightly packed molecules
  • Gases: Low density, widely separated molecules
• What is the density of water?

  1000 kg/m³
• What is the density of air at sea level?

  1.3 kg/m³
• What is the aim of the first experiment in determining density?

  • To determine densities of regular objects
  • Use measurements of their dimensions
• What is the aim of the second experiment in determining density?

  • To determine densities of irregular objects
  • Use a displacement technique
• What is the resolution of a digital balance?

  0.01 g
• What is the first step in measuring the density of regularly shaped objects?

  Place the object on a digital balance
• What should be done after measuring the mass of the object?

  Measure the object's dimensions
• What is the method for measuring the density of irregularly shaped objects?

  Use a displacement technique
• What is the first step in measuring the density of irregularly shaped objects?

  Place the object on a digital balance
• What should be done after placing the object in the eureka can?

  Measure the volume of displaced water
• What is the final step in both experiments for determining density?

  Calculate the density using mass and volume
• What is the equation to calculate density?

  ρ = m / V
• What does ρ represent in the density equation?

  Density in kg/m³
• What is the aim of Experiment 2?

  To determine densities of irregular objects
• What is the independent variable in Experiment 2?

  Different irregular shapes / mass
• What is the dependent variable in Experiment 2?

  Volume of displaced water