Podcast
Questions and Answers
A student is using a hand-cranked generator to power a light bulb. Which of the following energy transfers is LEAST likely to occur?
A student is using a hand-cranked generator to power a light bulb. Which of the following energy transfers is LEAST likely to occur?
- Some of the mechanical work is dissipated as thermal energy due to friction within the generator.
- The light energy produced is perfectly converted back into mechanical energy, assisting the student's hand motion. (correct)
- Electrical energy in the light bulb is converted into light and thermal energy.
- Mechanical work from the student's hand is converted into electrical energy in the generator.
A bouncy ball is dropped from a height. Upon impact with the floor, it compresses, then rebounds. Considering the moment of impact and compression, what energy transfer occurs?
A bouncy ball is dropped from a height. Upon impact with the floor, it compresses, then rebounds. Considering the moment of impact and compression, what energy transfer occurs?
- Kinetic energy is converted entirely into gravitational potential energy.
- Gravitational potential energy is converted entirely into kinetic energy.
- Elastic potential energy is converted entirely into kinetic energy.
- Kinetic energy is primarily converted into elastic potential energy and some thermal energy. (correct)
An electric motor lifts a heavy block at a steady rate. Which statement BEST describes the primary energy transfers involved?
An electric motor lifts a heavy block at a steady rate. Which statement BEST describes the primary energy transfers involved?
- Electrical energy is converted into kinetic energy, but energy losses prevent full conversion to gravitational potential energy. (correct)
- Electrical energy is converted into kinetic energy, which is then entirely converted into gravitational potential energy.
- Electrical energy is converted into thermal energy, which then becomes kinetic energy.
- Gravitational potential energy is converted into electrical energy to power the motor.
Flashcards
Energy
Energy
The capacity for doing work. Energy can be transferred, dissipated, or stored in different forms but cannot be created or destroyed.
System
System
An object or a group of objects that can exchange energy with its surroundings.
Energy store
Energy store
Different ways in which energy can be stored, such as chemical, kinetic, gravitational potential, etc.
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 extended or short periods.
- Whenever a system changes, the way energy is stored changes.
Examples of Energy Transfers
- A boat moving through water demonstrates the transfer of chemical energy into kinetic energy.
- In an electric kettle, electricity increases the internal energy of the element, subsequently increasing the water's internal (thermal) energy and temperature.
- A swinging pirate ship ride shows kinetic energy being transferred into gravitational potential energy.
Types of Energy Transfer
- Energy can be transferred through heating.
- Energy can be transferred by waves.
- Energy can be transferred through electric current.
- Energy can be transferred by a force moving an object.
Potential Difference (Voltage)
- Potential difference measures the energy given to charge carriers in a circuit.
- Units of potential difference are volts (V).
- Voltage between two points enables electric current flow.
- Energy is released by the material, decreasing its internal energy.
- Infrared radiation emitted from the Sun into space exemplifies this.
Work
- Doing 'work' signifies energy transfer.
- Examples of 'work' include a grazing cow, a firing catapult, and a boiling kettle.
Diagrams of Energy Transfer
- Transfer diagrams use boxes to represent energy stores.
- Arrows in transfer diagrams represent energy transfers.
- In a child on a slide, gravitational energy is transferred as mechanical work is done to increase speed and overcome friction.
- The energy shifts from gravitational potential energy to kinetic energy and internal energy.
Sankey Diagrams
- Sankey diagrams use arrows that split to show energy transfer into different stores.
- Arrow width scales with the amount of energy.
- These diagrams are useful when the amount of energy in each source is known.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
