P1-Energy

• energy is transferred between stores
• thermal, kinetic, gravitational potential, elastic potential, chemical, magnetic, electrostatic, nuclear
• energy is transferred mechanically by a force doing work
• energy is transfered electrically work done by moving charges
• energy is transfered by heating or by radiation for example light or sound
• a system is a group of objects
• boiling water in a kettle and water is the system. energy is transferred to the water by heating into the waters thermal energy store
• the initial force exerted by a person to throw a ball upwards does work. it causes an energy transfer from the chemical energy store of the persons arm to the kinetic energy store of the ball and arm
• movement means energy in an objects kinetic energy store
• the energy in the kinetic energy store depends on the objects mass and speed the greater the mass the faster its going the more energy there will be in its kinetic store kinetic energy = 1/2 x mass x speed ^2
• raising objects store energy in gravitational potential energy stores
• transfer of energy to the gravitational potential energy store of the raised object the higher the object is lifted the more energy is transferred to this store
• when something falls energy from its gravitational potential energy store is transferred to its kinetic energy store
• stretching can transfer energy to elastic potential enegy stores
• stretching or squashing an object can transfer energy to its elastic potential energy store so long as its limit of proportionality has not been exceeded elastic potential energy
• specific heat capacity is to raise 1kg by 1 c
• more energy need to be transferred tot he thermal energy stores of some materials to increase their temperature more than other change in thermal energy
• required practical

  A) mass

  B) surroundings

  C) thermometer

  D) initial temperature

  E) stop watch

  F) thermal energy store

  G) every minute

  H) current

  I) transfered to the

  
• conservation of energy says that energy can be transferred usefully, stored or dissipated but can never be created or destroyed
• power is the rate of doing work
• power is measured in watts and one watt is equal to 1 joule of energy transferred per second power = energy transferred / time power = work done / time
• lubrication reduces frictional forces when something moves there is usually one frictional force acting against it and lubricants can be used to reduce the friction between the objects surfaces when they move
• heating can occur by conduction and convection. conduction is the particles vibrating more and more to collide with each other during these collisions energy is transferred between particles kinetic energy stores. and because liquids and gases can flow the warmer and less dense region will rise above denser, cooler regions so energetic particles move away from hotter to cooler regions
• insulation, double glazed windows and draught excluders reduces the rate of energy transfers by heating
• efficiency = useful output energy transfer / total energy transfer efficiency = useful power output / total power input
• non renewable energy resources will runout eventually. fossil fuels and nuclear fuel such as coal oil and gas. however they produce most of our energy
• renewable energy resources will never run out. the sun, wind, water waves, hydro electricity, bio fuel, tides and geothermal
• wind turbines produce no pollution but do spoil views and are very loud
• solar panels are very expensive but do not damage the environment
• geothermal energy is energy in underground energy stores its possible in volcanoes or hot rocks that lie quite near the surface. the source of the energy is in slow decays of various radioactive elements. the drawbacks are they are expensive and there arent many suitable locations
• hydro electric power uses falling water. it usually requires the flooding of a valley by building a big dam water is allowed out through turbine. it creates no pollution however it does damage the environment and initial cost are high
• wave power is wave powered turbines located around the coast and are connected to generators. it creates no pollution but does disturb the sea bed and very unreliable due to lack of wind
• tidal barrages uses sun and moons gravity as the tide comes in the water is then allowed out through turbines at a controlled speed. no pollution but prevents access for boats and spoils the view
• bio fuel are made from plants and waste. they are expensive and create deforestation however they are fairly reliable