Where Does Energy Hide — and How Does It Move?

Think about a moment just before you drop a ball from a height. The ball isn't moving yet. Nothing looks like it is happening. And yet, the moment you let go, the ball crashes to the ground and bounces. Where did all that action come from? Energy was already there — hidden, waiting, stored. Scientists have discovered that energy never appears from nowhere and never simply vanishes. It shifts from one place, or 'store', to another. Your job today is to become an energy detective and follow the trail.

Energy is the ability to make something happen — to cause a change. Physicists organise energy into named stores depending on how it is held. The main energy stores are: • Kinetic store — energy held by anything that is moving. A speeding cyclist, a flying football, and even the molecules vibrating inside a warm cup of tea all have kinetic energy. • Gravitational potential store — energy held by an object because of its height above the ground. The higher and heavier the object, the larger this store. • Elastic potential store — energy stored when a material is stretched or squashed, like a compressed spring or a drawn bow. • Chemical store — energy locked inside the bonds between atoms in a substance. Food, fuel, and batteries all hold chemical energy. • Thermal store — energy held due to the temperature of an object. The hotter something is, the larger its thermal store. • Electromagnetic store — energy carried by light and other radiation, including the sunlight that warms your skin. • Nuclear store — energy held inside the nucleus of an atom, released in stars and nuclear power stations. Energy does not jump between stores by magic. It moves along a pathway. Scientists recognise four main transfer pathways: • Mechanical work — a force acting through a distance (pushing, pulling, hitting). • Electrical work — charges moving around a circuit. • Heating — energy moving from a hotter object to a cooler one by conduction, convection, or radiation. • Radiation — energy carried by waves (light, sound, infrared). A key law: energy is always conserved. The total amount of energy in a closed system never changes — it only moves between stores. Some transfers are useful; others result in energy spreading to the surroundings as thermal energy (often called 'wasted' energy, though it still exists).