physics energy

• Energy conversion


  The process of transforming one form of energy into another
• Energy conversion in an electric car


  1. Electrical energy from batteries

  2. Converted to kinetic energy to turn the wheels and move the car
• Forms of energy that can be converted into each other

  • Electrical energy
  • Chemical energy
  • Radiation energy
  • Nuclear energy
  • Heat
• Energy conversion in an electric car

  1. Chemical energy from batteries

  2. Converted to electrical energy

  3. Converted to kinetic energy
• Energy flow chart


  A diagram showing the different energy conversions taking place
• Gravitational energy

  Temporarily stored energy that an object has when it is at a certain height
• Gravitational energy


  • Equal to the work required to get the object to that height
  • Can be used to power a car back down a mountain without the engine
• Power


  The amount of energy a device converts per second
• Efficiency


  The ratio of useful energy output to total energy input, expressed as a percentage
• Incandescent lamps have an efficiency of about 5%
• 95% of the energy used by incandescent lamps is converted into non-useful heat
• CFL, fluorescent and LED lamps are more efficient than incandescent lamps
• Law of conservation of energy

  Energy is never lost or gained; it can only be converted from one form into another
• 100% efficiency is not feasible in practice
• you calculate the efficiency by deviding the useful energy with the total energy, and then time a 100%
• the electrical energy is calculated by the product of power and time.
• electrical energy can be used with diffrent units. power into kilowatts (kW), time into hours(h). the outcome will than be in kilowatthour (kWh)