Energy Stores & Transfers

Energy Stores

• Energy is a quantity that needs to be transferred to an object to either perform work on it or increase its temperature.
• The unit of energy measurement is the joule (J).
• Energy is frequently discussed within the context of an energy system.
• In the realm of physics, a system is defined as an object or a collection of objects.
• In physics, delineating the system serves to narrow down the variables to focus solely on what is pertinent to the observed situation.
• A system can span from something as immense as the entire universe to something as diminutive as an apple resting on a table.
• When a system is in a state of equilibrium, there are no alterations, and consequently, no changes occur.
• Any modification to a system results in the transfer of energy.

Example Scenarios

• If an apple is placed on a table and the table is suddenly removed, the apple falls due to the disruption in equilibrium.
• As the apple falls, potential energy is converted into kinetic energy, illustrating energy transfer in action.
• Objects possess energy stored in various energy stores, such as gravitational potential energy or chemical energy.

Energy Stores Table

Energy Transfers

• Energy moves between different stores through various pathways of energy transfer, which encompass:
  • Mechanical: Involves the physical movement of objects or substances, such as when a force is applied to an object causing it to move.
  • Electrical: Entails the flow of electrical charge through a conductor, like the transmission of electricity through wires.
  • Heating: Occurs when energy is transferred due to a temperature difference, typically resulting in the warming of an object or substance.
  • Radiation: Involves the transmission of energy through electromagnetic waves, such as light or heat emitted by the Sun.
• These pathways of energy transfer facilitate the movement of energy between different stores, allowing for diverse forms of energy to be utilized and transformed.

Energy Transfer Pathways Table

• An instance of energy transfer through heating is when a hot coffee transfers heat to a mug and then to cold hands, resulting in a temperature change.