Podcast
Questions and Answers
What happens to energy when a system changes?
What happens to energy when a system changes?
- Energy is destroyed.
- Energy remains constant and unchanged.
- The way some or all of the energy is stored changes. (correct)
- Energy is created.
Which of the following is an example of energy transfer?
Which of the following is an example of energy transfer?
- A closed book on a table.
- Water is heated in an electric kettle. (correct)
- A car parked in a garage overnight.
- A rock sitting still on the ground.
What does 'doing work' scientifically mean?
What does 'doing work' scientifically mean?
- No energy is involved.
- Energy has been transferred. (correct)
- Energy has been created.
- Energy has been destroyed.
Flashcards
Energy
Energy
The capacity for doing work. It is neither created nor destroyed, but transferred, dissipated, or stored.
System
System
An object or group of objects that can undergo energy transfers and storage changes.
Energy store
Energy store
Different ways in which energy can be stored, including chemical, kinetic, gravitational potential, elastic potential, and thermal stores.
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 fractions of a second.
- Energy transfers occur constantly when a system changes.
- System change affects how energy is stored.
Examples of Energy Transfers
- A boat moves through water: chemical energy becomes kinetic energy.
- Boiling water in an electric kettle: electrical energy increases the internal energy of the element, thereby increasing the internal (thermal) energy of the water, which raises its temperature.
- A swinging pirate ship ride: kinetic energy converts into gravitational potential energy.
Types of Energy Transfer
- Heating
- By waves
- Electric current
- By a force moving an object
Potential Difference
- A measure of the energy given to charge carriers in a circuit, measured in volts (V).
- The voltage facilitates electric current flow between two points.
- Energy is released by a material, reducing its internal energy.
- Infrared radiation from the Sun emits into space.
- 'Work' is the transfer of energy, demonstrated by examples like 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 transforms into mechanical work, increasing speed and overcoming friction.
- Energy shifts from gravitational potential energy to kinetic and internal energy, raising the temperature of the child and the slide.
Sankey Diagrams
- Begin as a single arrow that splits to show energy distribution.
- Useful when the amount of energy in each source is known.
- Arrow width is scaled to represent the amount of energy.
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