Energy transfers and Resources Flashcards
What does the Law of conservation of energy state
Energy can be transferred usefully, stored or dissipated but it cannot be created or destroyed.
what is a sankey diagram
Sankey diagrams provide an overview of the main energy flows and how they contribute to the global energy balance of a certain territory
is the total quantity of energy in the universe constant or changing
Constant
Why is it that during energy transfers in a closed system, there is no net change to the total energy
Like any other system, energy can be transferred in a close system. However, since energy cannot exchange with the surroundings, there will be no net change to the total energy in a closed system.
Wasted energy
Wasted energy is energy that is not usefully transferred
Wasted energy equation
Total energy - useful energy
Dissipation
Dissipation is a term that is often used to describe ways in which energy is wasted. Any energy that is not transferred to useful energy stores is said to be wasted because it is lost to the surroundings. Electrical cables warming up are a good example of this because it transfers thermal energy into the surroundings
what are 7 types of energy stores
Kinetic, Electrical, Chemical, Gravitational potential, Elastic potential, Thermal (Internal) and Magnetic
conduction
Conduction is the process by which heat energy is transmitted through collisions between neighboring atoms or molecules. Conduction occurs more readily in solids and liquids, where the particles are closer together than in gases, where particles are further apart.
Thermal Insulation
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way to stop unwanted energy transfer. A common way in which energy is wasted is through thermal energy. For example, when a house is heated, energy can be transferred through the windows, doors and walls. In order to combat this, houses are often insulated and windows are double glazed.
Lubrication
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way to stop unwanted energy transfer. Energy can be lost due to friction. a lubricant is a substance such as oil or grease that helps to reduce friction between surfaces.
control of friction
what happens when thermal conducticity of a material increases
The rate of thermal conductivity across the material will increase.
rate of cooling in buildings
thermal conductivity of doors, walls and windows can result in energy loss. Reducing thermal conducticity will reduce the amount of thermal energy leaving buildings.
one way it can be achieved is through increasing the thickness of walls, such as putting an airgap between layers in walls and potentially fill the airgap with foam to reduce the rate of thermal conductivity
metals are good conductors of electricity. True or False?
True
metals conduct at different paces, some are better than others.
what happens to the particles of a heated/warm solid.
if the solid is hot, the particles will vibrate. Due to the density of the particles, vibrations are easily moved on.
Thermal conductivity.
Definition not needed for GCSE syllabus but helps being known
Measure of rate of at which thermal energy transfers through a material
metals are good thermal conductors, wood, plastic and cotton are not
Energy Efficiency equation
Useful Power output / Total power input
Energy transfer efficiency equation
Useful output energy transfer / Total input energy transfer
How to achieve efficiency of an intended energy transfer.
This can be achieved by reducing wasted energy transfers so more of the input energy is usefully transferred. Mechanical devices can be made more efficient through lubrication to reduce the friction between moving parts of a machine and increase the amount of useful energy transferred.
