Physics density

• Solids


  • Particles are very close together and arranged in a regular pattern
  • Particles vibrate but do not move from place to place
• Liquids


  • Particles are still close together but not arranged in a regular pattern
  • Particles can move around each other
• Gases


  • Particles are very far apart and not arranged in any pattern
  • Particles are moving very rapidly
• Density


  The mass for a given volume
• Solids


  Usually have very high density because particles are packed closely together
• Liquids


  Usually have high density because particles are close together
• Gases


  Have low density because particles are very far apart
• Specific heat capacity


  The amount of energy required to raise the temperature of one kilogram of a substance by one degree Celsius
• Calculating energy required to increase temperature

  1. Mass in kg

  2. Specific heat capacity in J/kg/°C

  3. Temperature change in °C
• Calculating mass of water in hot water bottle

  1. Thermal energy change = 756,000 J

  2. Specific heat capacity of water = 4200 J/kg/°C

  3. Temperature change = 60°C

  4. Mass = 3 kg
• Internal energy


  The energy stored inside a system by the particles, including kinetic energy of particles due to movement and potential energy of particles due to forces and bonds
• Heating a solid substance

  1. Temperature rises

  2. Temperature stops rising, becomes horizontal

  3. Solid changes state to liquid (melting)

  4. Temperature starts rising again
• Latent heat


  The energy needed for a substance to change state
• Melting point


  The temperature at which a solid changes state to a liquid
• Heating a liquid


  1. Temperature rises

  2. Temperature stops increasing, becomes horizontal

  3. Liquid changes state to gas (boiling)

  4. Temperature starts rising again
• Boiling point


  The temperature at which a liquid changes state to a gas
• Cooling a gas


  1. Temperature decreases

  2. Gas changes state to liquid (condensation)

  3. Liquid changes state to solid (freezing)

  4. Temperature continues decreasing
• You can find plenty of questions on heating and cooling graphs in the revision workbook