Energy Stores & Transfers - VOCABULARY Flashcards

A set of vocabulary flashcards covering key terms in energy stores, transfers, and related concepts from the lecture notes.

Energy store

The location where energy is stored in a system (e.g., kinetic, gravitational, elastic, magnetic, electrostatic, chemical, nuclear, thermal).

Kinetic store

Energy stored in moving objects due to their motion.

Gravitational potential store

Energy stored when an object is lifted in a gravitational field; depends on height and mass.

Elastic potential store

Energy stored when something is stretched, squashed, or bent.

Magnetic store

Energy stored in interacting magnetic materials.

Electrostatic store

Energy stored due to interactions between charged objects.

Chemical store

Energy stored in chemical bonds; released or absorbed during chemical reactions.

Nuclear store

Energy stored in atomic nuclei; released during nuclear reactions.

Thermal store

Energy stored due to an object's temperature; hotter objects have more energy in this store.

System (physics)

An object or group of objects being studied; boundaries define what is included.

Equilibrium (physics)

A state where nothing changes in the system; no energy transfers occur.

Energy transfer pathway

A route by which energy moves from one store to another (e.g., mechanical, electrical, heating, radiation).

Mechanical working

Energy transferred by a force causing movement (pushing, pulling, etc.).

Electrical working

Energy transferred by electric current moving through a potential difference.

Heating (energy transfer)

Energy transferred from a hotter object to a colder one by heating mechanisms (e.g., conduction).

Radiation (energy transfer)

Energy transferred by electromagnetic waves (e.g., infrared).

Conduction

Transfer of thermal energy through solids by particle vibration and electron movement; metals conduct well due to free electrons.

Convection

Transfer of thermal energy by the movement of a fluid (liquid/gas) due to density differences; forms convection currents.

Conductor

Material that transfers energy by heating well; typically metals.

Insulator

Material that reduces energy transfer by heating; contains trapped air; poor conductor.

Thermal conductivity

A measure of how easily a material conducts heat; high in metals, low in insulators.

Conservation of energy

Energy cannot be created or destroyed; total energy in a closed system remains constant; energy in equals energy out.

Total energy input / total energy output

In a closed system, total energy entering equals total energy leaving; energy is never lost but can dissipate as waste.

Wasted energy

Energy transferred to surroundings that is not useful.

Useful energy output

The portion of total energy that ends up in the desired store or for the intended use.

Efficiency

Efficiency = useful energy output / total energy output × 100%; a measure of how well energy transfers are used.

Sankey diagram

A visual diagram of energy transfers with arrows whose widths are proportional to energy amounts, showing energy in, useful energy out, and wasted energy.

Infrared radiation

Electromagnetic radiation emitted by all objects above 0 K; hotter objects emit more IR and it can be detected by infrared cameras.

Black body (absorption/emission)

Idealized surface that is a good absorber and emitter of thermal radiation.

Colour and radiation (absorption/emission)

Colour affects how well a surface absorbs and emits thermal radiation (e.g., black absorbs/emits well; white and shiny surfaces absorb/emit poorly).

Vacuum

Space with no matter; conduction and convection cannot occur; radiation can still transfer energy.

Insulation

Material that reduces energy transfer by conduction and convection; depends on conductivity, density, and thickness.

Fibreglass

Glass fibre insulation that traps air to reduce heat transfer.

Cavity wall insulation

Insulating material or foam inserted into wall cavities to reduce heat transfer.

Greenhouse gases (contextual)

Gases released from burning fossil fuels that contribute to global warming.

Convection current

A circulating flow in a fluid where hot, less dense regions rise and cooler, denser regions sink, driven by heating.

Thermal equilibrium

State in which objects at the same temperature exchange no net heat energy with their surroundings.