Topic 1: Energy Stores, Transfers and Systems

Flashcards specifically focusing on the vocabulary and core concepts of Energy, including types of stores, methods of transfer, conservation principles, and calculations for power and efficiency.

Kinetic energy store

Energy stored in objects that are moving; calculated using the formula $E_k = \frac{1}{2}mv^2$.

Gravitational potential energy store

The energy stored in an object due to its position above the ground; calculated as $E_p = mgh$.

Elastic potential energy store

Energy stored in objects that are being stretched or compressed, such as a spring or a car hitting a tree.

Electrostatic energy store

One of the eight types of energy stores involving the interaction of electric charges.

Thermal energy store (internal)

Energy associated with the temperature of an object; in many systems, energy is dissipated (wasted) into this store.

Magnetic energy store

Energy stored within a magnetic field.

Chemical energy store

Energy stored in chemical bonds, such as energy in an arm before throwing a ball or in a battery.

Nuclear energy store

Energy stored in the nucleus of an atom.

Mechanical transfer

An energy transfer involving a force doing work.

Electrical transfer

Work done by moving charges.

Heating transfer

Energy transfer caused by a temperature difference; for example, from a kettle's heating element to water.

Radiation transfer

Energy transfer through waves, such as light or sound.

Work done

A term used interchangeably with energy transferred.

System

A single object or a group of objects.

Closed system

A system where no energy or matter is transferred in or out, meaning there is no overall change in total energy.

Conservation of Energy

The principle that energy can be transferred usefully, stored, or dissipated, but it can never be created or destroyed.

Dissipated energy

Energy that is wasted by being transferred to a store that is not useful, usually the thermal energy store of the surroundings.

Specific Heat Capacity

The amount of energy needed to raise the temperature of $1\,kg$ of a substance by $1^{\circ}C$.

Power

The rate of energy transfer or the rate of doing work, measured in watts ($W$).

Watt ($W$)

A unit of power where one watt is equal to one joule of energy transferred per second ($1\,J/s$).

Power formula (Energy)

$P = \frac{E}{t}$, where $E$ is energy transferred in joules and $t$ is time in seconds.

Power formula (Work)

$P = \frac{W}{t}$, where $W$ is work done in joules and $t$ is time in seconds.

Efficiency (Energy)

$$\text{Efficiency} = \frac{\text{Useful output energy transfer}}{\text{Total input energy transfer}}$$

Efficiency (Power)

$$\text{Efficiency} = \frac{\text{Useful power output}}{\text{Total power input}}$$