The 4 Energy Transfer Pathways

🔬 The 4 Energy Transfer Pathways

Energy doesn't teleport between stores — it moves via specific pathways:

🔧 Mechanical Work — Forces Causing Movement

What it is: Energy transferred when a force causes an object to move in the direction of the force.

The equation: Work done = Force × Distance (W = F × d)

• Lifting a box — your muscles do work against gravity
• Pushing a trolley — you do work to increase its kinetic energy
• Stretching a spring — you do work to store elastic PE
• Friction — does negative work, transferring KE to thermal

⚡ Electrical Work — Charges Moving in Circuits

What it is: Energy transferred when electric charges flow through a circuit.

• Battery powering a motor — chemical energy → electrical → kinetic
• Mains electricity heating a kettle — electrical work → thermal energy

🔥 Heating — Energy from Hot to Cold

What it is: Energy transferred from a hotter region to a cooler region due to temperature difference.

• Conduction — particles vibrate and pass energy to neighbours; best in solids, especially metals
• Convection — hot fluid rises (less dense), cold fluid sinks; only in liquids and gases
• Radiation — infrared waves; works through vacuum (how Sun's energy reaches Earth)

🌊 Radiation (Waves) — Energy Carried by Waves

What it is: Energy transferred by electromagnetic waves or sound waves.

• Light — carries energy from Sun to Earth; absorbed by surfaces
• Infrared — thermal radiation; how you feel heat from a fire
• Sound — mechanical wave; carries energy through air to your ears