Physics: Conservation of Energy Concepts

Conservation of Energy

• Energy cannot be created or destroyed, only transferred.
• Total energy before a transfer equals total energy after.
• Energy transfer methods include light, sound, and electricity.

Measuring Energy

• Temperature is measured in degrees Celsius (°C), representing average energy.
• Thermal energy represents total energy.
• A warm bath has more thermal energy than a heated kettle, even if the kettle is hotter.

Heating

• Heating increases particle kinetic energy, causing faster vibration.
• Heating an object's energy need depends on mass, material, and temperature change.
• Equilibrium occurs when objects have equal thermal energy.

Energy Transfer

• Thermal energy transfers via conduction, convection, and radiation.

Conduction

• Particles in solids transfer energy through collisions.

Convection

• In liquids and gases, heating causes particles to move faster, become less dense, and rise.
• Cooler, denser particles sink, creating a convection current.

Radiation

• Energy transfer without particles, through waves.
• All objects emit radiation, the amount depending on temperature and surface properties (color, smoothness).
• Radiation can be absorbed or reflected.

Power

• Power is the rate of energy transfer (energy per second).
• Energy bills are measured in kilowatt-hours (kWh).
• Converting kWh to joules requires converting time to seconds.

Energy Bills Calculation

• A 2 kW device uses 4 kWh.
• Energy bills include fuel costs, power station costs, staff, and infrastructure.

Reducing Energy Bills

• Use fewer or more efficient appliances.
• Insulation reduces thermal energy loss in homes to lower energy needs.

Work, Energy, and Machines

• Work done = Force × Distance
• Simple machines, like levers and gears, make work easier, but conserve energy.

Energy in Food and Activities

• Food energy varies; examples including 200 kJ/100g apple, 1000 kJ/100g chips.
• Activity energy needs vary; examples including 6 kJ/minute sitting, 60 kJ/minute running.

Renewable Resources

• Renewable resources (wind, tidal, wave, hydroelectric, geothermal, biomass, solar) produce greenhouse gases while being built but not when used and are sustainable.

Non-Renewable Resources

• Non-renewable resources (coal, oil, gas) formed from fossilized remains are not reusable and will eventually run out.
• They are used in thermal power stations to heat water, producing steam and turning turbines that spin generators.
• Fossil fuels produce greenhouse gases.

Energy Sources and Transfers

• Energy is stored in chemical form in food and fuels.
• Energy is measured in joules (J).
• Different activities require different amounts of energy.

Explore the fundamental concepts of energy conservation, transfer methods, and measurement. This quiz covers topics such as conduction, convection, and the relationship between temperature and energy. Test your understanding of how thermal energy behaves in different scenarios.