Using Energy

Using Energy

Forms of Energy
1. Chemical Energy (fuel including food and is released during chemical reactions
2. Kinetic Energy
3. Gravitational potential Energy (due to position)
4. Elastic Potential Energy( energy through strain and stretch)
5. Thermal Energy
6. Electrical Energy
7. Light Energy
8. Sound Energy
9. Dropping an object: Gravitational energy at the top, turns to Kinetic when hits the floor then Heat and Sound energy
Conservation of Energy
1. means that no energy is created or destroyed
  1. I.E : Total Energy before transfer = total energy after transfer
  2. energy supplied = useful energy +wasted energy
Useful Energy and Wasted Energy
1. useful energy is energy transferred to where it is wanted in the form it is wanted!
2. wasted energy is energy not usefully transfered
  1. Wasted energy is dissipated (spread out) to surrroundings
    1. Useful energy eventually transfers to the surroundings too
      1. the more energy is spread out the less useful it is
        it is hard to get back energy and gases in the surroundings therefore not useful
      2. useful energy for wheels of car is transferred to energy heating tyres and that energy is transfered to the actual road
    2. heat is spread out of the tv
Energy and Efficiency
1. Weight is measured in Newtons (n) ( 1 kilogram on Earth = 10N)
2. Energy is measured in Joules (J) energy needed to lift 1N by 1 metre is 1joule
3. Efficiency = (useful energy transferred / total energy supplied) x 100
  1. Examples
    1. Lightbulb = for every 100J of energy 5J of energy is transferred to light..
      1. efficiency = 5/100 x100
        5% efficient
    2. energy needed to carry two skiers to top of mountian by chairlift is 240000J
      1. motor is 40% efficient
        calculate wasted energy
        0.4 = useful energy/ total energy
        0.4 = 240 000 / x
        0.4x= 240 000
        x= 240 000/ 0.4
        total energy imput = 600 000
        600 000 - 240 000 = wasted energy output
        = 360 000

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