AQA GCSE Physics

Revision Notes

1.1.1 Energy Stores & Transfers

Systems in Physics

  • Energy is a property that must be transferred to an object in order to perform work on or heat up that object
  • It is measured in units of Joules (J)
    • This is regardless of what type of energy is stored ie. kinetic or chemical
  • Energy will often be described as part of an energy system
  • In physics, a system is defined as:

An object or group of objects

  • Therefore, when describing the changes within a system, only the objects or group of objects and the surroundings need to be considered
  • A thermodynamic system, for example, can be isolated, closed or open
    • An open system allows the exchange of energy and matter to or from its surroundings
    • A closed system can exchange energy but not matter to or from its surroundings
    • An isolated system does not allow the transfer of matter or energy to or from its surroundings

Types of systems, downloadable IB Chemistry revision notes

A system can be open, closed or isolated

Energy Stores & Transfers

Energy Stores

  • Energy can be stored in different ways, and there are changes in the way it is stored when a system changes
  • The principle of conservation of energy states that:

Energy cannot be created or destroyed, it can only be transferred from one store to another

  • This means that for a closed system, the total amount of energy is constant
  • There are many different ways that energy can be stored, these are shown in the table below:

Types of Energy Stores Table

Energy Transfers

  • A system can change between stores through different energy transfer mechanisms
  • Examples of these are:
    • Mechanical
    • Electrical
    • Heating
    • Radiation
  • These are described in the table below:

Types of Energy Transfers Table

  • An example of a thermal energy transfer is a hot coffee heating up cold hands

Thermal energy transfer, downloadable AS & A Level Physics revision notes

Thermal energy is transferred from the hot coffee to the mug and to the cold hands

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