conservation of energy

• kinetic energy (J) = 1/2 x mass (KG) x velocity^2(m/s)
• energy can be transferred, stored, dissipated but not destroyed or created
• change in GPE (J) = mass(kg) x gravitational field strength (g) x change in height (m)
• gravitation potential energy - the energy an object has due to its position above Earth, energy due to its height.

  e.g. plane and kites
• 8 main stores of energy are :

  • magnetic
  • internal (thermal)
  • chemical
  • kinetic
  • electrostatic
  • elastic potential
  • gravitational potential
  • nuclear
• magnetic energy - stored when repelling poles have been pushed closer together or when attracting poles have been pulled further apart.

  e.g. fridge magnets or compasses
• internal (thermal) - the total amount of kinetic energy and potential energy of all the particles in the system.

  e.g. human bodies, hot coffees, ice particles vibrating slowly but still have energy
• chemical energy - energy stored between chemical bonds, such as those in molecules

  e.g. foods, muscles and electrical cells
• kinetic energy - energy of moving objects

  e.g. runners and comets
• electrostatic energy - stored when repelling charges have been moved closer together or when attracting charges have been pulled further apart.

  e.g. thunderclouds and battery
• elastic potential energy - energy stored when object is squashed or pulled

  e.g. rubber band, catapults, inflates baloons
• nuclear energy - energy stored in nucleus of an atom

  e.g. Uranium nuclear power, nuclear reactors
• energy can transfer, and you can also get wasted energy (usually thermal energy which has dissipated into the surroundings)
• in a closed system, no energy is wasted as there's no external forces acting on it
• to reduce waste of energy :

  • lubricate systems - so there's less friction and less heat created
  • thermal insulation - so less heat is lost to the surroundings
• efficiency = useful energy transferred by the device / total energy supplied by device
• mechanical wasted energy :

  "thermal energy dissipates into the surroundings"
• non renewable energy resources

  • more reliable compared to something like hydroelectricity or solar energy which depend heavily on the weather which can be out of control
  • used more for car-scale energy supplies due to the large energy output per kilogram of fuel
• renewable energy :

  • finite resources will soon eventually run out completely because of the rapid use we're using them and them not being produced at the same rate - renewables development has become more important
• higher thermal conductivity means greater rate of energy transfer