Podcast
Questions and Answers
Which of the following statements is true about energy?
Which of the following statements is true about energy?
- Energy can be both created and destroyed.
- Energy can be destroyed but not created.
- Energy cannot be created or destroyed. (correct)
- Energy can be created but not destroyed.
What happens when a system changes?
What happens when a system changes?
- Energy is created.
- The way energy is stored remains the same.
- Energy is destroyed.
- There is a change in the way some or all of the energy is stored. (correct)
Which of the following is an example of energy transfer?
Which of the following is an example of energy transfer?
- A car sitting still on a road.
- A rock resting on the ground.
- Water boiling in an electric kettle. (correct)
- A stationary bicycle.
Flashcards
Energy
Energy
The capacity for doing work; it exists in different 'stores' and can be transferred, dissipated, or stored. It cannot be created or destroyed.
System
System
An object or group of objects considered together; when it changes, there is a change in how its energy is stored.
Energy Store
Energy Store
The different ways in which energy can be stored, such as chemical, kinetic, gravitational potential, elastic potential, and thermal.
Study Notes
- Energy exists in different 'stores' and cannot be created or destroyed.
- Energy can be transferred, dissipated, or stored in various forms.
- Energy can remain in a store for varying durations, from millions of years to fractions of a second.
- Energy transfers occur continuously with any system change, altering how energy is stored.
- Examples of energy transfers include a boat moving through water, water boiling in a kettle, and a swinging pirate ship.
- In an electric kettle, electricity increases the internal energy of the element, which then increases the internal (thermal) energy of the water, raising its temperature.
- A swinging pirate ship transfers kinetic energy into gravitational potential energy.
Types of Energy Transfer
- Energy transfers occur through heating, waves, electric current, or a force moving an object.
- Potential difference (voltage) measures the energy given to charge carriers in a circuit, with units in volts (V).
- Voltage causes electric current to flow between two points.
- Materials 'give out' energy, causing a decrease in their internal energy, such as infrared radiation from the Sun.
- 'Work' scientifically means energy has been transferred, as seen in examples like a grazing cow, a firing catapult, and a boiling kettle.
Diagrams
- Diagrams illustrate energy transfer between stores.
- Transfer diagrams use boxes for energy stores and arrows for energy transfers; an example is gravitational energy from a child at the top of a slide being transferred into kinetic and internal energy.
- Sankey diagrams show how energy in a system is transferred into different stores.
- Sankey diagrams begin as one arrow that splits, indicating how energy is distributed, useful when the amount of energy in each source is known.
- The width of the arrow in a Sankey diagram is scaled to represent the amount of energy.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
