Conservation and Dissipation of Energy

This section delves into the law of conservation of energy and explores how energy can be dissipated in various scenarios.

Quote: "Energy can be transferred usefully, stored or dissipated but it cannot be created or destroyed."

This fundamental principle, known as the law of conservation of energy, underpins much of physics and is crucial for GCSE Physics energy revision.

Example: In bungee jumping, energy is dissipated as thermal energy through friction with air particles and the stretching effects of the bungee rope.

The concept of 'work done' is introduced as the transfer of energy from one store to another.

The guide provides practical ways to reduce thermal energy transfer from a house:

• Using insulating materials in walls
• Installing double-glazed windows
• Adding loft insulation
• Constructing buildings with materials of low thermal conductivity
• Building houses with thick walls

Two experiments are described to investigate thermal insulation:

1. Effectiveness of different insulating materials:

   • Place a small beaker inside a larger one
   • Fill the small beaker with hot water
   • Use different insulating materials in the larger beaker
   • Measure temperature changes over time

2. Effect of insulation thickness:

   • Wrap a beaker of hot water with varying layers of newspaper
   • Measure temperature changes over time for each thickness

Vocabulary: A fluid is defined as a substance in which particles are free to move, encompassing both liquids and gases.

Energy Stores and Transfers

This section introduces the fundamental concepts of energy in GCSE Physics, focusing on energy stores, transfers, and systems.

Vocabulary: Energy stores are locations where energy can be stored, while energy transfers describe how energy moves between these stores.

The main energy stores include:

• Magnetic
• Chemical
• Thermal
• Elastic potential
• Gravitational potential
• Kinetic
• Nuclear
• Electrostatic

Energy transfers occur through:

• Mechanical means
• Electrical processes
• Heating
• Infrared radiation
• Light or sound waves

Definition: An open system allows energy and matter to enter or leave, while a closed system prevents energy from entering or leaving.

The concept of specific heat capacity is introduced, along with a practical experiment to determine it:

Example: To determine specific heat capacity:

1. Place a beaker on a balance and zero it
2. Add oil to the beaker and record its mass
3. Insert a thermometer and immersion heater into the oil
4. Record the starting temperature
5. Insulate the beaker with foam
6. Connect a joulemeter and power pack
7. Leave for 30 minutes
8. Record the final temperature and energy used

Highlight: Common errors in this practical include heat loss to the surroundings, incomplete energy transfer to the oil, and inaccurate temperature readings. These can be mitigated through better insulation, ensuring full submersion of the heater, and using electronic probes.