P1

• Energy is transferred between stores:

  • Kinetic energy stores
  • Thermal energy stores
  • GPE stores
  • Elastic potential energy stores
  • chemical energy stores
  • magnetic energy stores
  • electrostatic energy Stores
  • Nuclear energy Stores
• Energy can be transferred by heating

  e.g: Boiling kettle

  1. Energy is transferred electrically to the kettle which transfers energy by heating the waters thermal energy store

  or by doing work

  e.g.: car braking

  2. The friction between a car's brakes and its wheels does work as it slows down. this causes an energy transfer from the wheels Kinetic energy stores to the thermal energy store of its surroundings
• Kinetic energy = 1/2 mv 2

  Kinetic energy (J) = half mass (Kg) x speed squared
• GPE= mgh

  GPE= mass x gravitational feild Strength x hight

  (Kg) (N/kg) (m)
• For a falling object when theres no air resistance

  energy Lost from the gp.e. store = energy gained in the kinetic energy store
• As long as the limit of proportionality hasn't been exceeded,

  Ee = 1/2 ke2

  elastic potential energy (J) = half spring Constant (N/M)X extention (m) squared
• Specific heat capacity

  • Amount of energy needed to raise the temperature of 1 kg of a substance by 1 degree
  • change in thermal energy (J) = mass (Kg) X specific heat capacity (J/kg °C ) x temp change (°C)
• How to investigate Specific Heat capacities

  1. Get a block of the material you are inspecting with two holes (for the heater and thermometer)

  2. Measure the mass of the block

  3. Wrap it in an insulating layer to reduce the energy transferred from the block to its surroundings

  4. Insert the thermometer and heater into the block

  5. Measure the initial temp of the block

  6. Set the potential difference of the power supply to 10 v

  7. Turn on the power supply

  8. Start a stop watch

  9. Take readings of the temp and current every minute for 10 minutes

  10. Turn off the power supply

  11. Calculate the power supplied to the heater using p= VI

  12. Plot a graph

  13. Calculate heat capacity = 1÷(gradient x the mass of the block)
• Energy can be transferred, Stored or dissipated, but can never be created or destroyed
• In systems that aren't closed, energy can be dissipated in non - useful ways, like when your phone heats up while you are using it
• power is the rate of doing work

  p= E/T

  Power (w)= Energy transferred (J) ÷ time (s)

  OR

  p= W/T

  power (w) = work done (J) ÷ time (s)
• Lubrication:

  • Reduces friction between object's surfaces when they move
  • usually liquids (like oil)
• Convection:

  • when particles are free to move (like in a liquid) the space between individual particles increases
  • so warmer and less dense region will rise above denser, cooler regions. so energetic particles move away from hotter to cooler regions
• Insulation:

  • Reduces rate of energy transfer by heating
  • thick walls made from a material with a low thermal conductivity
  • cavity walls- walls with an air gap in the middle that reduces Conductors
  • Double -glazed Windows
  • Draught excluders
• Efficiency:

  efficiency= useful output energy transfer ÷ total input energy transfer

  efficiency= useful power Output ÷ total power input
• energy resources for heating:

  Non-renewable:

  • Natural gas is used to heat water which is then pumped into radiators throughout the home
  • coal is commonly burnt in fireplaces
  • electric heaters, which use electricity generated from non-renewable sources

  Renewable:

  • Geothermal heat pump
  • Solar water heaters to fill radiators
  • burning bio- fuel
• Wind turbines:

  • Each turbine has a generator inside, which is turned to produce electricity by the blades
  • NO pollution (except for a little bit when they are made)
  • can spoil the View
  • you need 1500 to replace one coal-fired power station
  • can be very noisy
  • only produce electricity 85 percent of the time
• solar cells:

  • Generate electric current directly from sunlight
  • Used in remote places to power road signs and satellites
  • No pollution
  • Not very reliable
• Geothermal power

  • possible in volcanic areas where the source of the energy is the Slow decay of radioactive elements
  • Free energy that does very little damage to the environment
  • Aren't many suitable locations for a power plant
• Hydro-electric power

  • requires the flooding ot a valley by building a big dam. water is allowed out through terbines
  • Big impact on the environment due to the rotting vegetation and loss of habitats
  • can provide an immediate responce to an increased demand for electricity
• wave power:

  • lots of small wave powered turbines around the coasts
  • can disturb the seabed and habitats of marine animals
  • can be a hazard to boats
  • fairly unreliable
  • Not for large scale
• Tidal Barrages

  • Big dams buit across river estuaries with turbines in them. As the tide comes in, it fills up the estuary. The water is then allowed out at a controlled speed
  • prevents free access by boats
  • alters the habitat of wild life, e.g. wading Birds
  • Height of waves can vary
  • Doesn't work when water level is the same each side, Which happens 4 times a day
• Environmental problems from non-reliables

  • Greenhouse effect
  • Burning coal and oil releases sulfur dioxide which causes acid rain
  • coal mining makes a mess of landscapes, especialy open cast mining
  • oil spillages cause serious environmental problems
  • Nuclear waste is dangerous and nuclear power is risky