P1 - Energy

• What are the different energy stores?

  • magnetic
  • internal (thermal)
  • chemical
  • kinetic
  • electrostatic
  • elastic potential
  • gravitational potential
  • nuclear
• How can energy be transferred between the stores?

  • mechanical working – when a force is applied to move an object through a distance
  • electrical working – when charge flows (electricity)
  • heating – when energy is transferred between hotter and colder regions
  • radiation – when energy is transferred as a wave, for example as light or sound
• What is wasted energy and where does it go?

  During any energy transfer some energy is wasted, normally as heat. Eventually all energy is transferred to heat and is dissipated into the surroundings. The amount of energy that is used to do a useful job in an energy transfer is a measure of the efficiency of the system or device.
• Efficiency equation

  Efficiency = useful power out ÷ total power in

  No units
• What are Sankey diagrams?

  Sankey diagrams start off as one arrow that splits into two or more points. This shows how all the energy in a system is transferred into different stores.

  Sankey diagrams are really useful when the amount of energy in each of the energy sources is known. The width of the arrow is drawn to scale to show the amount of energy.

  
• Gravitational Potential Energy equation

  gravitational potential energy = mass x gravitational field strength x vertical height raised

  Ep=m * g * h (Remember as hairy mountain goats)
• Kinetic Energy equation

  Kinetic energy = 0.5 x mass x (speed)2

  Ek=0.5 * m * v2
• Why will theoretical velocity never be reached?

  In summary, falling objects cannot reach terminal velocity in the real world due to the drag force that eventually equals the force of gravity, preventing further acceleration.
• What is maximum theoretical velocity?

  A theoretical velocity describes the maximum speed an object falling from a given height would reach if there was no air resistance.
• Elastic Potential Energy equation

  elastic potential energy = 0.5 × spring constant × (extension)2

  Ee = 0.5 * k * e2
• Specific Heat Capacity equation

  Change in energy = mass x specific heat Capacity x change in temperature

  
• What are the equations for power?

  Power=Energy/time (E/t)

  Power=Current x Resistance squared

  Power=Voltage x Resistance
• Ways to reduce unwanted energy loss?

  1. Thermal insulation. A common way in which energy is wasted is through thermal energy. In order to combat this, houses are often insulated and windows are double glazed.
  2. Lubrication. Energy can be lost due to friction. In order to combat this, you can put oil on the chain.
  3. Streamlining. When objects travel through the air, they experience air resistance. In order to combat this, we streamline objects. Streamlining is when we change the shape of an object so that it doesn’t feel the effects of air resistance as much.  
• Factors affecting thermal conductivity of a building

  Factors affect in thermal conductivity of building insulation materials are reviewed. Temperature, moisture content, and density are the most important factors. Other factors include thickness, air velocity, pressing, and aging time.
• Advantages and Disadvantages of renewable energy

  Most renewable energy resources are clean, because they do not produce any pollution and cheap because their energy supplies do not have any cost. Hydroelectric power stations, as well as tidal and wave generators, are very reliable, and both produce large amounts of electricity.

  At the present time, most renewable energy generators are expensive to set up. Also, sources such as wind turbines and solar cells rely heavily on the weather and if the conditions aren't perfect then they won't generate energy.
• Advantages and Disadvantages of non-renewable energy

  Fossil fuels, such as nuclear and coal, are reliable sources of energy, but they are expensive to build and dismantle. These non-renewable fuels, which have taken millions of years to form, release carbon dioxide into the atmosphere, contributing to global warming. Oil and gas are the first to run out, followed by coal. Nuclear power stations, while relatively cheap, are expensive to build and dismantle, and their radioactive waste poses a health hazard.