Energy at work | Year 7 Physics (Cambridge) PDF Download

Introduction to Energy Transfer

• Definition: Energy is never created or destroyed but transferred between different forms and objects.
• Importance: Fundamental concept in physics, underpins various topics in the course.

Forms of Energy

• Thermal/Internal Energy:
  • Definition: Heat energy trapped within an object.
  • Example: Heating element of a kettle transferring energy to water.
• Kinetic Energy:
  • Definition: Energy associated with movement or motion.
  • Example: Ball moving after being kicked.
• Gravitational Potential Energy:
  • Definition: Energy due to an object's position in a gravitational field.
  • Example: Water stored in a dam.
• Elastic Potential Energy:
  • Definition: Energy stored in a stretched or compressed elastic object.
  • Example: Stretched spring in a toy car.
• Chemical Energy:
  • Definition: Energy stored in chemical bonds.
  • Example: Energy released from burning fuel.
• Magnetic Energy:
  • Definition: Energy associated with magnetic fields.
  • Example: Magnets attracting or repelling.
• Electrostatic Energy:
  • Definition: Energy due to electric charges.
  • Example: Static electricity shock.
• Nuclear Energy:
  • Definition: Energy released from breaking apart atomic nuclei.
  • Example: Energy from nuclear reactions.

Energy Transfer Mechanisms

• Mechanical Transfer:
  • Definition: Energy transfer through physical movement or forces.
  • Example: Pushing a cart uphill.
• Electrical Transfer:
  • Definition: Energy transfer through electrical currents.
  • Example: Powering devices with electricity.
• Heat/Radiation Transfer:
  • Definition: Energy transfer through heat or radiation.
  • Example: Sunlight warming the Earth.

Systems and Energy Interaction

• Open System:
  • Definition: System where matter and energy can exchange with the surroundings.
  • Example: Boiling water in a kettle.
• Closed System:
  • Definition: System isolated from its surroundings, exchanging only energy.
  • Example: Sealed thermos with hot coffee.

Work Done in Energy Transfer

• Mechanical Work Done:
  • Definition: Energy transferred through physical force.
  • Example: Lifting weights.
• Electrical Work Done:
  • Definition: Energy transferred through electrical currents.
  • Example: Lighting up a bulb.

Conclusion

Energy is crucial in understanding how objects function and interact with their environment. It exists in various forms and can be transferred between them through different mechanisms.