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Energy and Efficiency

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Clement Tay
Clement Tay

The document discusses the concepts of potential energy, kinetic energy, and the principle of conservation of energy. It explains that: 1) When gravitational potential energy is fully converted to kinetic energy or vice versa, the principle of conservation of energy states that the amounts must be equal. 2) In a non-ideal pendulum or other system, some energy is always lost to heat and friction during conversions between potential and kinetic energy, so the full amount is not regained. 3) Efficiency refers to the ratio of useful energy output to the total energy input in a system, expressed as a percentage. It accounts for energy lost to other forms like heat.

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WHEN G.P.E. IS CONVERTED ENTIRELY TO K.E. OR VICE VERSA... Ek = 遜mv2 Ep = mgh By Principle of Conservation of Energy, Ek = Ep 遜mv2 = mgh 遜v2 = gh v = 2gh
2 Principle of Conservation of Energy and the non-ideal pendulum 1. Lost in EP Gain in EK + Thermal energy (friction) 2. Lost in EK Gain in EP + Thermal energy (friction) Height gained is lower than the original because some of the energy has been converted to thermal energy. (1) (2) The pendulum eventually comes to a stop. Video - Ballistic pendulum
EFFICIENCY What does efficiency refer to?
EFFICIENCY Recall Senoko Power Station: Note the conversion of energy from one form to another
EFFICIENCY Do you agree? The chemical energy of the fuel is fully converted to electrical energy because the Principle of Conservation of Energy states that energy cannot be created nor destroyed.
EFFICIENCY Some of the energy is converted to heat, light and sound. The energy conversion is thus not 100% Wouldnt this violate the Principle of Conservation of Energy?
EFFICIENCY No, because the total sum of heat, light, sound and electrical energy is equal to the chemical energy of the fuel
LIGHT BULB
EFFICIENCY In a system, the ratio of useful energy output to the total energy input is known as the efficiency of the system. Efficiency is expressed as a percentage
EFFICIENCY Calculate the efficiency of the light bulb.

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Energy and Efficiency

  • 1. WHEN G.P.E. IS CONVERTED ENTIRELY TO K.E. OR VICE VERSA... Ek = 遜mv2 Ep = mgh By Principle of Conservation of Energy, Ek = Ep 遜mv2 = mgh 遜v2 = gh v = 2gh
  • 2. 2 Principle of Conservation of Energy and the non-ideal pendulum 1. Lost in EP Gain in EK + Thermal energy (friction) 2. Lost in EK Gain in EP + Thermal energy (friction) Height gained is lower than the original because some of the energy has been converted to thermal energy. (1) (2) The pendulum eventually comes to a stop. Video - Ballistic pendulum
  • 4. EFFICIENCY Recall Senoko Power Station: Note the conversion of energy from one form to another
  • 5. EFFICIENCY Do you agree? The chemical energy of the fuel is fully converted to electrical energy because the Principle of Conservation of Energy states that energy cannot be created nor destroyed.
  • 6. EFFICIENCY Some of the energy is converted to heat, light and sound. The energy conversion is thus not 100% Wouldnt this violate the Principle of Conservation of Energy?
  • 7. EFFICIENCY No, because the total sum of heat, light, sound and electrical energy is equal to the chemical energy of the fuel
  • 9. EFFICIENCY In a system, the ratio of useful energy output to the total energy input is known as the efficiency of the system. Efficiency is expressed as a percentage
  • 10. EFFICIENCY Calculate the efficiency of the light bulb.