1.1 Energy

• energy is never used up - its only transferred and stored
• energy stores :

  thermal , kinetic , gravitational potential , elastic potential , chemical , magnetic , electrostatic , nuclear
• a system is a fancy word for a single object or a group of objects
• closed systems means that energy nor matter can enter or leave
• work can be done when current flows or by force
• kinetic energy = 1/2 X mass X speed^2
• gravitational potential = mass X gravitational field strength X height
• energy lost from the g.p.e store = energy gained in the kinetic energy store
• elastic potential energy = 1/2 X spring constant X extension
• specific heat capacity is a way of saying how hard something is to heat up
• change in thermal energy = mass X specific heat capacity X temperature change
• energy can be transferred or stored but it can never be created or destroyed
• power is the rate of energy transfer
• Power = energy transferred / time
• power = work done / time
• conduction is the process where vibrating particles transfer energy to neighboring particles
• convection is where energetic particles move way from hotter to cooler regions
• lubrication reduces frictional forces they prevent from tearing and damages
• insulation reduces the rate of energy transfer by heating
• most energy transfers involve some waste enrgy
• efficiency = useful output energy transfer / total input energy transfer x 100
• fossil fuels are non renewable resources

  coal , oil , natural gas
• renewable energy sources

  wind , the sun solar energy , water waves , hydro electricity , bio fuel , tides , geothermal
• wind power

  no pollution

  spoiling the view

  they can be noisy

  initial costs are high , no fuel or running costs

  no permanent damages
• solar cells

  no pollution

  very reliable sources, only in the daytime

  cannot increase the power output when the demand is high

  initial costs are high , but after its pretty much free
• geothermal power - underground thermal energy stores

  little damage to the environment

  hot rocks that lie near the earths surface

  not very many locations for power plants

  high cost
• hydro-electric power uses falling water

  requires flooding of a valley or a dam

  no pollution

  big impact because the flooding of the environment
• wave power

  set all around the coastline

  no pollution

  disturbing the seabed

  fairly unreliable
• tidal bar ridges

  big dams built across river estuaries

  the water is allowed to go out to the other side at the controlled speed

  no pollution

  expensive to set up
• bio fuels are made from plants and waste

  they can be all states and be used in the same way as fossil fuels

  fairly reliable

  very high cost

  may have a bad impact on the environment