Physics: Conservation of Energy Concepts

Study Notes

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.

Description

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.

Physics: Conservation of Energy Concepts

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Questions and Answers

Which energy source produces greenhouse gases only during its construction?

Fossil fuels can be reused and will last indefinitely.

How much energy does running use per minute?

The energy content of an apple is ___ kJ per 100g.

Match the following energy sources with their classification:

What does the law of conservation of energy state?

Thermal energy and temperature are the same thing.

What type of energy transfer occurs when particles collide in solids?

In a convection current, the ______ part rises while the cooler part falls.

Match the following methods of thermal energy transfer with their descriptions:

How is power defined in relation to energy?

What is the formula for work done?

Insulated houses require more power to maintain thermal energy.