AQA GCSE Physics Topic 1: Energy

Energy Stores

• A system refers to an object or a group of objects where energy storage changes during system alterations.
• When a ball rolls and strikes a wall, kinetic energy converts into sound energy.
• Vehicles converting kinetic energy to thermal energy while slowing down due to friction between brakes and wheels.

Calculating Energy

• Kinetic Energy Formula: ( E_k = \frac{1}{2} mv^2 )
  • m: mass (kg), v: speed (m/s), ( E_k ): kinetic energy (J).
• Elastic Potential Energy Formula: ( E_e = \frac{1}{2} ke^2 )
  • ( E_e ): elastic potential energy (J), k: spring constant (N/m), e: extension (m).
• Gravitational Potential Energy Formula: ( E_p = mgh )
  • ( E_p ): gravitational potential energy (J), g: gravitational field strength (9.8 m/s²), h: height (m).
• Specific Heat Capacity: energy = mass × specific heat capacity × temperature change.
  • ( \Delta E = mc\Delta T )
  • ( \Delta E ): change in thermal energy (J), m: mass (kg), c: specific heat capacity (J/kg°C), ( \Delta T ): temperature change (°C).

Power

• Power measures the rate of energy transfer or work done: ( P = \frac{E}{t} ) or ( P = \frac{W}{t} )
  • P: power (W), E: energy transferred (J), t: time (s), W: work done (J).
• A motor's power is determined by how quickly it can perform work, demonstrating faster energy transfer.

Energy Transfers

• Energy can be transferred, stored, or dissipated but not created or destroyed, leading to energy deemed ‘wasted’.
• Reducing waste involves:
  • Lubrication (e.g., oil in motors) to limit friction losses.
  • Thermal insulation (e.g., double glazing) to conserve thermal energy.

Thermal Conductivity

• Higher thermal conductivity allows heat to transfer efficiently, impacting energy transfer rates.
• Thick, low thermal conductivity walls reduce cooling rates; thin metal sheets lose heat quickly.

Efficiency

• Efficiency quantifies useful work relative to total energy input:
  • ( \text{efficiency} = \frac{\text{useful energy output}}{\text{total energy input}} )
• Enhancing efficiency involves reducing waste and recycling output energy.

Energy Resources

Main Energy Sources

• Non-renewable: fossil fuels (coal, oil, gas) and nuclear fuel.
• Renewable: biofuels, wind, hydroelectricity, geothermal, tidal, solar, and water waves.

Renewable vs. Non-Renewable

• Renewable sources replenish naturally; non-renewable provide high energy output but are finite.
• Renewable energy's significance is rising with finite fossil fuels; reliability can vary (e.g., solar and wind).

Main Energy Uses

• Key applications: transport, electricity generation, and heating.

Environmental Impact

• Energy extraction affects landscapes (e.g., fossil fuels) and can create visual pollution (e.g., wind turbines).
• Fossil fuels release harmful emissions; renewable sources like solar and wind produce electricity without emissions.

Patterns and Trends in Energy Use

• The Industrial Revolution marked fossil fuels as a principal energy source due to ease of mining and high energy output.
• Recent technology advancements have improved the usability of renewable energy sources.
• Balancing increasing energy demands with environmental considerations is complex and influenced by political, social, ethical, and economic factors.

Explore the key concepts of energy stores in this AQA GCSE Physics quiz focused on Topic 1. Understand how energy changes within different systems, such as a rolling ball and a slowing vehicle. Perfect for those studying for their higher tier physics exams.