Energy

• The temperature of a gas relates to the average kinetic energy of the molecules
• Internal energy


  Energy stored in a system by the particles in that system
• The particles in a gas collide with each other and the walls of their container without losing kinetic energy
• Density of materials = mass / volume
• Density is mass per unit volume
• Water is used in heating systems; if water had a low specific heat capacity, it would cool before reaching some radiators in the house
• Specific Latent Heat of Fusion is the energy required for a solid to change into a liquid with no temperature change
• Stretching an atom too far makes it move back, it now has kinetic energy
• Between a gas and its container, all forces exerted at 90° angles
• Heating changes internal energy by increasing kinetic energy
• The particles in a gas are constantly randomly moving
• Water, making up 70% of our body, needs high Specific Heat Capacity to regulate body temperature during exercise or exposure to cold temperatures
• Specific Heat Capacity is the amount of energy required to raise the temperature of one kilogram of a substance by 1°C
• Temperature increase

  Pressure is inversely proportional to the volume of gas (Boyle's Law)
• Specific Latent Heat of Vaporization is the energy required for a liquid to change into a gas with no temperature change
• Specific Heat Capacity of Water is high
• Power is the rate at which energy is transferred
• Heating changes state by increasing potential energy as particles increase separation
• Energy stores are different forms of energy
• Efficiency has no unit, written as a decimal or percentage
• Main energy stores

  • Kinetic
  • Chemical
  • Internal/Thermal
  • Gravitational potential
  • Magnetic
  • Electrostatic
  • Elastic potential
  • Nuclear
• Energy is always conserved
• The Principle of the Conservation of Energy: energy is in the same amount before and after an event, energy cannot be created nor destroyed
• Efficiency


  A way of expressing the proportion of energy that is usefully transferred in a process as a number
• Closed system: where all energy is used usefully, no energy dissipation
• Energy changes in systems

  Change in thermal energy = mass * specific heat capacity * temperature change
• Specific heat capacity

  The amount of heat energy required to raise the temperature of a unit mass of a substance by one degree Celsius
• Power is the rate at which energy is transferred or work is done
• Open system: where not all energy is usefully used, some dissipation