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