Energy 0.0 / 5 ? PhysicsEnergyGCSEAQA Created by: george_brightmanCreated on: 18-11-17 11:15 Stored Energy A system is an object or a group of objects. There are changes in the way energy is stored when a system changes. A moving object has kinetic energy. When it hits a wall the energy is transferred as kinetic energy to the wall, heat and sound energy. 1 of 3 Power Power is the rate at which energy is transferred. Power is the rate at which work is done. An energy transfer of 1 Joule/second = A power of 1 Watt. 2 of 3 Energy Transfers in a System Energy can be: Transferred Usefully Stored Dissipated Energy cannot be created or destroyed. In a closed system, there is no net change to the total energy. In all system changes, energy is dissipated, so that it is stored in less useful ways. Dissipated energy is often described as being wasted. Lubrication and thermal insulation are two ways to reduce unwanted energy transfers. The higher the thermal conductivity of a material, the higher the rate of energy transfer by conduction across the material. The rate of a cooling building is affected by the thickness and thermal conductivity of its walls. 3 of 3
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