Energy

• Kinetic Energy Equation


  1/2 x mass x speed^2
• Gravitational Potential Energy


  mass x gfs x height
• Power


  Power = energy transferred / time = work done / time
• Suggested video: Isaac Physics Kinetic Energy Equation: https://isaacphysics.org/pages/covid19_gcse_archive?stage=all#3

  
• Suggested reading: Electricity - 2.4.3 The National Grid (GCSE Physics AQA) - Study Mind
• Kinetic Energy


  The energy stored in objects that are moving
• Gravitational Potential Energy


  The energy stored in objects raised above the ground
• Chemical Energy


  The energy stored in fuel, food and batteries
• Thermal Energy


  The energy stored by hot objects
• Elastic Potential Energy


  The energy stored by stretched or squashed object
• Power


  Power is defined as the rate at which energy is transferred or the rate which work is done
• Conservation of energy


  In a closed system, energy canot be created or destroyed. The total energy is constant
• Thermal energy transfer, also known as heat transfer, occurs when energy is transferred from one object to another as a result of a temperature difference between the two objects.
• Extension- How much it is stretched or squashed
• The higher the thermal conductivity of a material ther higher the rate of energy transfer by conduction across the material.
• A good insulator has low thermal conductivity so that little energy is transferred through it by conduction.
• Thermal Conductors


  Materials that conduct heat easily, like metals (copper, aluminum)
• Thermal Insulators


  Materials that resist heat conduction, like most plastics and glass (Styrofoam, fibreglass)
• Most energy comes from burning fossil fuels. Used for electricity and transport systems.
•  Renewable-A resource that is replaced at the rate its is used
• Reliable- A resource that can generate electricity no matter the time of day and weather
• Renewable energy sources


  Biofuels

  Wind

  Hydroelectricity

  Solar

  Geothermal

  Tidal

  Wave
• Fossil fuel Power Stations


  Boiler- burning fossil fuel heats water, which produces steam

  Turbine- steam turns the turbine

  Generator- turbines generate electricity

  Transformer- changes the potential difference
• Efficiency


  Useful energy output / total energy input
• Power


  Current x Voltage
• Power

  Current^2 x resistance
• Potential difference


  Current x Resistance
• Law of conservation of energy


  Energy cannot be created or destroyed.
• Friction causes energy to be transferred to thermal energy stores
• To reduce friction, you can use a lubricant like oil or remove the air articles from around the system.
• A bungee jumper never returns to its original position. This is because energy is dissipated as thermal energy.
• Work is done when energy is transferred from one store to another.
• Efficiency


  Useful power output energy transfer/total input energy transfer

  OR

  Useful power output/Total power input
• Efficiency cannot be greater than 1
• Uses of energy


  Transport

  Electricity

  Heating
• Advantages to fossil fuels

  Reliable

  Release lots of energy

  They are abundant and cheap

  They are versatile
• Disadvantages to fossil fuels

  Releases lots of carbon dioxide

  Non renewable, they will run out
• Nuclear power is nonrenewable
• Advantages to nuclear power

  Does not release carbon dioxide

  Very reliable
• Nuclear power disadvantages


  Power plants contain highly dangerous radioactive materials

  They have to be dismantled which is expensive and takes many years

  Generates radioactive waste which needs to be stored for thousands of years before safe