Energy is all around us and is essential for everything we do. It’s a property that needs to be transferred to an object to perform work or to heat it up. Energy is measured in joules (J) or kilojoules (kJ). In this topic, we’ll learn about different energy stores, how energy is transferred, and how to calculate different types of energy.
1. Energy Stores #
Energy can be stored in different ways. We call these different ways “energy stores”. Objects can have different types of energy stored in them depending on their position, movement, or composition.
Types of Energy Stores #
Kinetic Store #
Moving objects have kinetic energy stored in them. The faster an object moves, the more kinetic energy it has.
Elastic Potential Store #
Stretched or compressed objects store elastic potential energy.
Gravitational Potential Store #
Objects that are lifted up against gravity store gravitational potential energy.
Magnetic Store #
Magnetic materials store energy in their magnetic fields.
Chemical Store #
Substances store energy in chemical bonds. During chemical reactions, energy can be transferred into or away from the substance.
Thermal Store #
All objects have thermal energy related to their temperature. The hotter an object, the more energy in its thermal store.
2. Energy Transfers #
Energy doesn’t disappear or appear out of nowhere – it transfers from one store to another through different pathways.
Energy Transfer Pathways #
| Transfer Type | Description |
|---|---|
| Mechanical | Energy transferred by forces causing movement (like pushing, pulling) |
| Electrical | Energy transferred by electric current flowing through conductors |
| Heating | Energy transferred due to temperature difference (from hot to cold) |
| Radiation | Energy transferred by waves (like light, sound, or electromagnetic waves) |
Examples of Energy Transfers #
Battery Powering a Torch #
(Battery)
(Torch Bulb)
(Environment)
When a torch is switched on, chemical energy stored in the battery is transferred through electrical pathways to the bulb, where it is converted to light energy and thermal energy.
A Falling Object #
When an object falls, the gravitational potential energy it had when it was higher up is transferred to kinetic energy as it falls. The higher the object starts, the more gravitational potential energy it has to transfer to kinetic energy.
