Energy Resources and Transfers
Coal might be cheap and plentiful right now, but it's a non-renewable energy resource that will eventually run out and releases harmful gases when burned. Compare this to renewable energy sources like solar, wind, and tidal power - they'll never run out, though they can be unreliable and expensive to set up initially.
Energy doesn't just disappear - it gets transferred between different energy stores. When a moving car slows down, kinetic energy (movement) transfers to the thermal energy store of the brakes through mechanical forces. Similarly, when you heat water with an electric kettle, electrical current transfers energy to the water's thermal store.
There are eight main energy stores you need to know: kinetic (moving objects), gravitational potential (lifted objects), elastic potential (stretched/squashed objects), thermal (hot objects), chemical (food, fuel, batteries), nuclear, magnetic, and electrostatic. Energy transfers through four main methods: heating, waves, electric current, and mechanical forces.
Key Concept: In a closed system, the total energy always stays the same - it just moves between different stores. This is called conservation of energy, and it's fundamental to understanding physics.
The greenhouse effect happens because gases like carbon dioxide, methane, and water vapour trap heat in our atmosphere. Human activities like burning fossil fuels, deforestation, and livestock farming increase these greenhouse gas levels, causing Earth's temperature to rise.
