4b-Energy transfers Flashcards
chemical energy can be stored in the following ways:
Chemical Energy – Stored in fuels, food, and batteries.
kinetic energy can be stored in the following ways:
Kinetic Energy – Energy of moving objects.
gravitation potential enegry can be stored in the following ways:
Gravitational Potential Energy (GPE) – Stored due to height above ground.
elastic potential can be stored in the following ways:
Elastic Potential Energy – Stored in stretched or compressed objects.
theraml energy can be stored in the following ways:
Thermal Energy – Stored in hot objects.
magnetic energy can be stored in the following ways:
Magnetic Energy – Stored in magnetic fields.
electtrostatic energy can be stored in the following ways:
Electrostatic Energy – Stored between charged objects.
Nuclear energy can be stored in the following ways:
Nuclear Energy – Stored in atomic nuclei.
different ways energy can be transferred Mechanically
mechanically - – When a force moves an object (e.g., pushing a box).
different ways energy can be transferred
electriacally
Electrically – When a charge moves in a circuit (e.g., powering a lamp).
different ways energy can be transferred
By heating
By Heating – Through conduction, convection, or radiation.
different ways energy can be transferred
By radiation
By Radiation – Via light or sound waves (e.g., sunlight warming the Earth).
Q: What is the principle of conservation of energy?
A: Energy cannot be created or destroyed, only transferred between stores.
Example: A pendulum converts kinetic energy to gravitational potential energy at the top of its swing, and vice versa.
Why are most energy transfers not 100% efficient?
A: Some energy is dissipated (spread out), usually as thermal energy due to friction or resistance.
Example: In a filament bulb, most of the electrical energy is lost as heat instead of light.
Q: What is a Sankey diagram?A
: A Sankey diagram represents energy transfers in a system:
Input energy is shown as a wide arrow.
Useful energy is shown as a forward arrow.
Wasted energy is shown as a smaller downward or side arrow.
Example:
In a car engine, chemical energy from fuel converts into kinetic energy (useful) and heat/sound (wasted).
How does convection work in everyday situations?A:
Boiling water: Hot water rises, cooler water sinks, forming convection currents.
Heaters in a room: Warm air rises, cool air falls, circulating heat.
How are emission and absorption of radiation affected by surfaces?A:
Dark, matte surfaces absorb and emit more infrared radiation.
Shiny, light-colored surfaces reflect radiation, reducing heat transfer.
Practical: Investigating Thermal Energy Transfer
Conduction
Method: Heat one end of a metal rod and observe how the other end gets warm.
Observation: Heat is conducted through the metal.
Practical: Investigating Thermal Energy Transfer
Convection
Convection
Method: Heat water in a beaker with dye and observe movement.
Observation: Warm water rises, cool water sinks, forming convection currents.
Practical: Investigating Thermal Energy Transfer
Radiation
Radiation
Method: Use a Leslie cube with different surfaces (black, white, shiny, matte) and an infrared detector.
Observation: Dark and matte surfaces emit and absorb more radiation.
Q: How can we reduce unwanted energy transfer?
Conduction: Use insulating materials (e.g., foam, wool, plastic).
Convection: Use trapped air layers (e.g., cavity wall insulation).
Radiation: Use shiny or reflective surfaces (e.g., thermal blankets).
Example: Houses use loft insulation, double-glazed windows, and cavity wall insulation to reduce heat loss.
