Physics topic 1

• Energy stores in a system change as the system changes
• Examples of energy transfers:

  • Ball rolling and hitting a wall: kinetic energy is transferred as sound
  • Vehicle slowing down: kinetic energy transfers to thermal due to friction between wheels and brakes
• Elastic potential energy formula: Ee = 1/2 * k * e^2, where Ee is in joules, k is spring constant in N/m, and e is extension in m
• Specific heat capacity is the energy required to raise the temperature of 1kg of a substance by 1°C or 1K
• Energy can be transferred usefully, stored, or dissipated but cannot be created or destroyed
• Efficiency is the ratio of useful work done to the energy supplied, often expressed as a percentage
• Main energy sources:

  • Non-renewable: fossil fuels, nuclear fuel
  • Renewable: biofuel, wind, hydro-electricity, geothermal, tidal, solar, water waves
• Renewable energy can be replenished as it is used, while non-renewable energy is used more for large-scale supplies
• Renewable energy has become more important due to the finite lifetime of fossil fuels
• Main energy uses: transport, electricity generation, heating
• Environmental impacts of energy sources include landscape destruction, harmful emissions, and visual impact
• Patterns and trends of energy use show the shift towards renewable energy due to technological advancements