Podcast
Questions and Answers
What happens to energy when a system changes?
What happens to energy when a system changes?
- The way energy is stored changes. (correct)
- Energy is created.
- Energy remains constant and unchanged.
- Energy is destroyed.
Which of the following is an example of energy transfer?
Which of the following is an example of energy transfer?
- Water freezing into ice.
- A rock sitting still on the ground.
- A boat moving through water. (correct)
- A tree growing taller.
What do the boxes in a transfer diagram represent?
What do the boxes in a transfer diagram represent?
- Energy transfers
- Energy stores (correct)
- Amount of Friction
- Distance travelled
Flashcards
Energy
Energy
The capacity for doing work. Energy cannot be created or destroyed, only transferred or stored.
System
System
An object or group of objects. When a system changes, there is a change in how energy is stored.
Energy Transfer
Energy Transfer
Infrared radiation, electricity, and forces doing work, are all ways in which energy moves from one place to another.
Study Notes
- Energy exists in different 'stores.'
- Energy cannot be created or destroyed.
- Energy can be transferred, dissipated, or stored in different forms.
- Energy can remain in the same store for varying durations, from fractions of a second to millions of years.
- Energy transfers occur continuously whenever a system undergoes changes, altering how energy is stored.
Examples of Energy Transfers
- A boat moving through water converts chemical energy into kinetic energy.
- Heating water in an electric kettle involves electrical energy increasing the internal energy of the element, which in turn increases the internal (thermal) energy of the water, raising its temperature.
- A swinging pirate ship ride demonstrates the transfer of kinetic energy into gravitational potential energy
Types of Energy Transfer
- Heating
- By waves
- Electric Current
- By a force moving an object
Potential Difference (Voltage)
- Potential difference measures the energy given to charge carriers in a circuit.
- Measured in volts (V).
- Voltage between two points causes electric current to flow.
- Energy is released by the material, decreasing its internal energy.
- Example: Infrared radiation from the Sun emitted into space.
Work
- Transfer of energy.
- Examples: A grazing cow, a firing catapult, and a boiling kettle all perform work by transferring energy.
Diagrams of Energy Transfer
- Used to illustrate energy transfer from one store to another.
- Two types: transfer diagrams and Sankey diagrams.
Transfer Diagrams
- Boxes represent energy stores.
- Arrows indicate energy transfers.
- Example: A child at the top of a slide.
- Gravitational energy stored in the child is transferred as mechanical work, increasing speed and overcoming friction.
- This results in a shift of energy from gravitational potential energy to kinetic energy and internal energy (raising the temperature of the child and the slide).
Sankey Diagrams
- Start as one arrow that splits into multiple points.
- Illustrate how all energy in a system is transferred into different stores.
- Useful when the amount of energy in each source is known.
- Arrow width is drawn to scale, representing the amount of energy.
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