Podcast
Questions and Answers
In the context of energy transfers, which scenario primarily involves a shift from kinetic energy to gravitational potential energy?
In the context of energy transfers, which scenario primarily involves a shift from kinetic energy to gravitational potential energy?
- Water flowing through a hydroelectric dam.
- A roller coaster car ascending the initial hill. (correct)
- A car accelerating on a flat road.
- An electric kettle heating water.
Which of the following statements best describes the energy transformations that occur when a bow and arrow are used to shoot at a target?
Which of the following statements best describes the energy transformations that occur when a bow and arrow are used to shoot at a target?
- Gravitational potential energy is converted into kinetic energy as the arrow is released, with the bow acting purely as a guiding mechanism.
- Kinetic energy from the archer's motion is stored as chemical energy in the bow, which is then released to propel the arrow.
- Elastic potential energy stored in the stretched bow is transferred into kinetic energy of the arrow, while a small amount is dissipated as thermal energy due to friction. (correct)
- Chemical energy in the archer's muscles is converted directly into kinetic energy of the arrow, with no intermediate energy stores involved.
A transfer diagram illustrates a sequence of energy transformations. If the initial energy store is chemical energy in a battery-powered flashlight, what is the most likely final energy store, considering energy dissipation?
A transfer diagram illustrates a sequence of energy transformations. If the initial energy store is chemical energy in a battery-powered flashlight, what is the most likely final energy store, considering energy dissipation?
- Predominantly thermal energy, due to inefficiencies in the electrical components and the bulb. (correct)
- Mainly kinetic energy, powering a small fan within the flashlight.
- Entirely light energy, as the purpose of a flashlight is illumination.
- An equal distribution of light energy and sound energy.
Flashcards
Energy
Energy
The capacity for doing work. It exists in different 'stores' and can be transferred, dissipated, or stored in various ways.
System (in Physics)
System (in Physics)
An object or group of objects under study where energy transfers and transformations are observed.
Energy Transfer
Energy Transfer
The movement of energy from one location or form to another, such as from a chemical store to kinetic energy or from kinetic energy to gravitational potential energy.
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 for a fraction of a second.
- Energy transfers happen continuously.
- Whenever a system changes, the way some or all of its energy is stored changes.
- Examples of energy transfers:
- A boat moves through the water as chemical energy converts to kinetic energy.
- Boiling water in a kettle converts electrical energy to internal energy which raises the water temperature.
- A swinging pirate ship ride which converts kinetic energy into gravitational potential energy, and vice-versa
- Energy transfers occur via four types:
- Heating
- Waves
- Electric current
- A force moving an object
- The potential difference (voltage) measures the energy given to charge carriers in a circuit, measured in volts (V).
- Voltage makes an electric current flow between two points.
- Energy is 'given out' by a material, decreasing its internal energy.
- Infrared radiation from the Sun is emitted into space.
- Doing 'work' means energy has been transferred.
- Examples of doing work: a grazing cow, a firing catapult, and a boiling kettle.
- Diagrams illustrate energy transfer from one store to another.
Transfer Diagrams
- Boxes represent energy stores.
- Arrows represent energy transfers.
- For example, a child at the top of a slide:
- Gravitational energy stored in the child is transferred as mechanical work; speeding up and working against friction.
- This shifts energy 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.
- Show 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 to represent the amount of energy.
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