Energy

• W = Fd

  Work done = force x distance
• Energy is transferred when work is done
• Work done against frictional forces causes energy transfer by heating
• Energy cannot be created or destroyed it can only be transferred from one form to another
• The total amount of energy is constant in a closed system
• Types of energy stores:-

  Kinetic

  Gravitational

  Elastic

  Thermal

  Electrostatic

  Magnetic

  Chemical

  Nuclear
• Ways of transferring energy stores:-

  Mechanically

  Electrically

  Heating

  Infrared radiation

  Sound or light waves
• Elastic potential energy

  Ee = 1/2 x k x e^2
• Gravitational potential energy

  Ep = m x g x h
• Kinetic energy

  Ek = 1/2 x m x v^2
• When the mass of an constant object is doubled, it will have twice the kinetic energy
• When an object traveling at twice the speed of another object with the same mass, it will have four times the kinetic energy
• Power is the rate at which energy is transferred or the rate at which work is done

  Power = work done [J] / time [s]
• Work done is the energy transfer that occurs when a force is used to move an object by a certain distance
• If an object is lifted up it will gain gravitational potential energy
• If an object falls it will lose gravitational potential energy
• Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed
• When energy is transferred only part of it may be usefully transferred; the rest is dissipated so that it is stored in less useful ways. This energy is often described as being ‘wasted’
• Friction and air resistance are forces that dissipate energy by heating the surroundings
• When a system changes, energy is transferred. A system is an object or group of objects
• A simple pendulum is an example of oscillating motion and energy is transferred between kinetic energy and gravitational potential energy
• Dissipated energy is lost to the surroundings
• Renewable resources are resources that can be replenished as they are used
• Non renewable energy resources are not replenished and so have a limited supply
• Examples of renewable resources are: solar, wind, hydroelectric, geothermal, biofuel, tidal, wave
• Examples of non renewable resources are oil, coal, gas and nuclear power
• Fossil fuels are formed from the remains of plants and animals that lived millions of years ago
• The main fossil fuel sources are coal, oil and natural gas
• Nuclear energy is the energy released by the splitting of the nucleus of an atom and is used to generate electricity
• PROS OF NUCLEAR ENERGY

  Doesn't produce greenhouses

  Can be used in any conditions

  Low operation cost
• CONS OF NUCLEAR ENERGY

  Limited fuel supply

  Produce radioactive waste

  Causes health issues
• Wind energy is generated by wind turbines which have blades that spin which convert kinetic energy into electrical energy
• PROS OF WIND ENERGY

  Low running costs

  No pollution

  Renewable
• CONS OF WIND ENERGY

  Noise pollution

  Threat to animals

  Dependent on the weather
• Solar energy is the energy from the sun that is used to generate electricity
• PROS OF SOLAR ENERGY

  Little to no maintenance

  Pollution free

  Low running costs
• CONS OF SOLAR ENERGY

  Needs a lot of space

  Expensive

  No solar energy at night
• Geothermal energy is a renewable energy source that is found in the earth's crust
• PROS OF GEOTHERMAL ENERGY

  Reliable

  High efficiency

  Unlimited supply
• CONS OF GEOTHERMAL ENERGY

  Produces greenhouse gases

  Expensive to build

  Can only be built in certain areas of the world