GCSE Physics - Energy

Historical Context of Energy

• Concept of energy emerged in the 19th century.
• Initially explained steam engine work output.
• Generalised to heat engines, chemical reactions, and biological systems.

Challenges and Innovations

• Limits of fossil fuels and global warming are critical issues.
• Ongoing work to reduce energy usage.

Energy Changes in a System

Energy Stores and Systems

• Definition: System = object or group of objects.
• Energy storage changes when a system changes.
• Common Situations:
  • Projected objects
  • Moving objects colliding
  • Accelerated objects
  • Vehicles slowing down
  • Boiling water in a kettle
• Calculations:
  • Changes in energy due to heating
  • Work done by forces or current flow

Changes in Energy

• Kinetic Energy Equation: [ \text{E}_k = \frac{1}{2} m v^2 ]
  • E_k: Kinetic energy (J)
  • m: Mass (kg)
  • v: Speed (m/s)
• Elastic Potential Energy Equation: [ \text{E}_e = \frac{1}{2} k e^2 ]
  • E_e: Elastic potential energy (J)
  • k: Spring constant (N/m)
  • e: Extension (m)
• Gravitational Potential Energy Equation: [ \text{E}_p = mgh ]
  • E_p: GPE (J)
  • m: Mass (kg)
  • g: Gravitational field strength (N/kg)
  • h: Height (m)_

Energy Changes in Systems

• Thermal Energy Change Equation: [ \Delta E = mc\Delta \theta ]
  • E: Thermal energy change (J)
  • m: Mass (kg)
  • c: Specific heat capacity (J/kg°C)
  • Δθ: Temperature change (°C)
• Practical Activity: Investigate specific heat capacity.

Power

• Defined as the rate of energy transfer or work done.
• Power Equations: [ P = \frac{E}{t} ] and [ P = \frac{W}{t} ]
  • P: Power (W)
  • E: Energy transferred (J)
  • W: Work done (J)
  • t: Time (s)

Conservation and Dissipation of Energy

Energy Transfers in Systems

• Energy can be transferred, stored, or dissipated, not created or destroyed.
• Energy Dissipation: Energy stored in less useful ways.
• Reduction of Unwanted Transfers: Use lubrication and thermal insulation.
• Practical Activity: Investigate thermal conductivity with different materials.

Efficiency

• Efficiency Equations: [ \text{efficiency} = \frac{\text{useful output energy}}{\text{total input energy}} ] [ \text{efficiency} = \frac{\text{useful power output}}{\text{total power input}} ]
• Increasing efficiency involves certain methods (Higher Tier).

National and Global Energy Resources

• Main Energy Sources: Fossil fuels, nuclear, bio-fuel, wind, hydroelectric, geothermal, tides, solar, water waves.
• Renewable vs Non-renewable:
  • Renewable: Can be replenished (e.g., solar, wind).
• Uses: Transport, electricity generation, heating.
• Environmental Impact: Analyze and compare impacts of different resources.
• Considerations: Science can identify issues but may be limited by political, social, ethical, or economic factors.

These notes provide a comprehensive overview of the key concepts in the GCSE Physics curriculum related to energy, covering the historical context, system changes, power, conservation, and global resources.