1 - Energy

• Closed System: A system that experiences no net change in its total energy when energy transfers occur within it
• Conservation of Energy: The law that energy can be transferred, stored or dissipated but never created or destroyed
• Efficiency: The ratio of useful output energy transfer to total energy input
• Elastic Potential Energy: The store of energy that stretched or compressed objects experience
• Elastic Potential Energy is directly proportional to the stiffness constant and to the square of the extension or compression
• Fossil Fuels: Coal, oil and gas
• Gravitational Potential Energy: The store of energy that all raised matter has
• Gravitational Potential Energy is directly proportional to the mass of the object, the distance that it is risen and the gravitational field strength at that point
• Joule: The unit used for energy
• One Joule is equal to the work done when a force of one Newton acts over a distance of one metre
• Kinetic Energy: The store of energy that all moving matter has
• Kinetic Energy is directly proportional to the object’s mass and to the square of its velocity
• Power: The rate at which energy is transferred, or at which work is done
• Renewable Energy Resource: An energy resource that can be replenished whilst it is being used
• Spring Constant: A measure of a spring’s stiffness
• The greater the value, the greater the force required to stretch or compress the spring by a given distance
• A system is an object or group of objects.
• When a system changes, the way energy is stored also changes.
• Kinetic Energy: Ek = 0.5 x mass x velocity^2
• It is easier to use energy resources due to increasing pressure to cope with the public’s increasing power demands but harder to solve environmental issues due to political, social, ethical and economic considerations.
• Extraction of Energy from Fossil fuels involves destroying landscapes.
• Use of Energy Sources from Fossil fuels releases harmful emissions.
• During the industrial revolution, fossil fuels became an important source of energy as it was easy to mine, and provided a lot of energy.
• Wind turbines can be considered an eyesore.
• Main Energy Uses include Transport, Electricity generation, and Heating.
• Only recently has renewable energy become more suitable due to technological developments.
• Solar and wind energy sources directly create electricity with no emissions.
• Elastic Potential Ee = 0.5 x spring constant x extension^2
• Gravitational Potential Energy: Ep = mass x gravitational field strength x height
• Renewable energy has become more important due to the finite lifetime of fossil fuels, and so their development has become more important.
• Thermal insulation, such as double glazing, reduces the amount of useful thermal energy lost.
• The efficiency is the ratio of the useful work done by a machine, engine, device, etc, to the energy supplied to it, often expressed as a percentage.
• Renewable energy is energy which can be replenished as it is used, for example, wind will never stop.
• The efficiency of a system can be increased by reducing waste output (lubrication, thermal insulation, etc.) and recycling waste output (absorbing thermal waste and recycling as input energy).
• If the walls of a building are thick and have low thermal conductivity, the rate of cooling is low.
• Non-renewable energy is used more for large-scale energy supplies due to the large energy output per kilogram of fuel, renewable resources cannot provide such a large amount of energy as easily.
• Lubrication in a motor reduces friction, so less energy is lost as heat through friction.
• Renewable energy is not always the most reliable as solar doesn’t work in bad weather or night and wind is only intermittent.
• If the walls of a building are thin metal sheets, heat would be lost very quickly.
• The higher the thermal conductivity of a material, the more easily heat is allowed to travel through the material, leading to a higher rate of energy transfer by conduction across the material.