Energy

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  • Created by: Ebod
  • Created on: 24-07-21 12:48
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  • Energy
    • Heating
      • Conduction
        • vibrating particles transfer energy to neighbouring particles via collisions
        • Thermal Conductivity
          • How quickly energy is transferred to a material via conduction
      • Convection
        • a region of a fluid is heated so the particles spread due to random diffusion
          • as the energetic particles spread, the heated region becomes less dense
            • the less dense, heated particles rise causing the cooler, less heated particles to sink
              • heated region above loses its energy and starts to sink, whereas the cooler region gets heated and rises
      • Insulation
        • something that reduces the rate of energy transfer by heating
        • thick walls out of a material with low thermal conductivity
          • cavity walls (walls with an air gap in between) as conductivity in fluids is low
            • cavity wall insulation (foam that wills the air gap)
            • loft insulation (fibreglass wool with pockets of trapped air)
          • double glazed glass (like cavity walls, has an air gap between)
      • Specific heat capacity
        • energy required to raise the temperature of 1kg of a substance by 1°C
          • C = E / (change in T x m)
    • Energy Sources
      • Renewable
        • Wind
        • Solar
        • Bio-fuel
        • Tides
        • Geothermal
        • Hydro-electric
      • Non-renewable
        • Coal
        • (Natural) Gas
        • Oill
        • Nuclear
          • isn't a greenhouse gas but makes radioactive waste
        • fossil fuels result in greenhouse gases, which contribute to global warming
    • Work, Power and Efficiency
      • Power
        • W = J / s
          • P = W / t
          • P = E / t
        • rate of energy being transferred or work being done
      • Energy conservation
        • Conservation of energy
          • energy cannot be created or destroyed, only transferred
        • Energy Dissipation
          • Not all energy transferred is useful; some is wasted
        • Efficiency
          • Efficiency = Useful energy output / Total energy Input
          • Efficiency = Useful Power output / Total Power input
          • Can be increased via lubrication and the use of thermal insulation
      • Work
        • Work Done = Energy Transferred via a force or when current flows
          • Work done = Voltage x Charge
            • J = VQ
          • Work done = Force x Distance
            • J = Nm
    • Changes in Energy Storea
      • kinetic energy
        • Ek = 1/2mv^2 
          • J = 1/2 x kg x (m/s)^2
      • thermal energy
        • change in E = m x c x change in T
          • J = kg x J/°C x °C
        • dissipated heat energy can be reduced via lubricants (e.g oil)
      • elastic potential energy
        • Ee = 1/2ke^2
          • J = 1/2 x N/m x m^2
      • gravitational potential energy
        • Eg = mgh
          • J = kg x N/m x m
      • chemical energy
      • nuclear energy store
      • magnetic energy
      • system
        • A system is an object or group of objects.

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