Podcast
Questions and Answers
Which of the following is described as an energy store?
Which of the following is described as an energy store?
- Kinetic energy (correct)
- Doing work
- Voltage
- Energy transfer
Which of these describes a way energy can be transferred?
Which of these describes a way energy can be transferred?
- Heating (correct)
- Energy store
- Gravitational potential energy
- Sankey diagram
In a transfer diagram, what do the arrows represent?
In a transfer diagram, what do the arrows represent?
- Systems
- Energy transfers (correct)
- Amount of energy
- Energy stores
Flashcards
Energy
Energy
The capacity for doing work. It is stored in different 'stores' and can be transferred, dissipated, or stored in various ways.
System
System
An object or group of objects where energy transfers and changes occur. Changes in a system indicate energy being transferred or stored differently.
Energy Transfer
Energy Transfer
Movement of energy from one energy store to another. It can occur through heating, waves, electric current, or a force moving an object.
Study Notes
- Energy exists in different 'stores'.
- Energy cannot be created or destroyed.
- Energy can be transferred, dissipated, or stored in different ways.
- Energy can remain in the same store for millions of years or a fraction of a second.
- Energy transfers occur whenever a system changes.
- A change in a system causes a change in how some or all of the energy is stored.
Examples of Energy Transfers
- A boat moving through water: chemical energy converts to kinetic energy.
- Heating water in an electric kettle: electricity increases the internal energy of the element, which in turn increases the internal (thermal) energy of the water, raising its temperature.
- Swinging pirate ship ride: kinetic energy converts into gravitational potential energy.
Four Types of Energy Transfer
- Heating
- By waves
- Electric current
- By a force moving an object.
Potential Difference (Voltage)
- The potential difference (or voltage) measures the energy given to charge carriers in a circuit.
- Units are volts (V).
- Voltage is the force that makes an electric current flow between two points.
- Energy is 'given-out' by the material, decreasing the material's internal energy.
- Infrared radiation emitted from the Sun into space exemplifies this.
- 'Work' is the scientific term for energy being transferred.
- Examples of 'work' include a grazing cow, a firing catapult, and a boiling kettle.
Transfer Diagrams
- Boxes represent energy stores.
- Arrows represent energy transfers.
- Example: a child at the top of a slide
- Gravitational energy stored in the child is transferred as mechanical work to speed up and overcome friction.
- Energy shifts from gravitational potential energy to kinetic and internal energy (raising the temperature of the child and the slide).
Sankey Diagrams
- Start as one arrow that splits into two or more.
- Illustrate how all energy in a system transfers into different stores.
- Useful when the amount of energy in each source is known.
- The width of the arrow is drawn to scale to represent the amount of energy.
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