Energy

Target Language or Knowledge:

Scientists have found it hard to define what energy is. Energy is not a substance or an object that you can touch or hold. But substances and objects can possess energy. A useful definition is that energy is something that is needed to make things happen. Energy can make things move or change. Energy makes things happen! There are many different forms of energy. Some types of energy involved stored energy, but other types of energy are involved in making things happen. Many objects have energy stored inside them because of their position (e.g. a skier at the top of a slope) or because of their nature (e.g. petrol or dynamite). Stored energy is called potential energy. That energy is available to make things happen. Energy associated with something moving or changing in some way can be called ‘active energy’ (e.g. the light energy associated with exploding fireworks). Radiant energy spreads out from a source as waves of energy travelling at the speed of light (300,000 km/s). There are different types of radiant energy, each with its own wavelength (distance between crests). Sound energy is produced by vibrating objects. The vibrations cause energy to travel as waves through the air away from the object. Sound waves travel at about 340 metres per second. Kinetic energy is possessed by all moving objects. The amount of kinetic energy an object possesses depends on its mass and how fast it is moving. Thermal energy (‘heat’) affects the movement of the particles (atoms and molecules) that make up matter. The more thermal energy particles possess, the faster and more freely they move. Gaining thermal energy causes a rise in temperature. Electrical energy is the flow of charged particles along a conductor such as a copper wire. This form of energy is carried by charged particles called electrons. Electrical energy cannot be seen, but its effects can be. Gravitational potential energy is possessed by objects that are above ground level. As the object is lifted, it gains gravitational energy. The stored energy is transformed into kinetic energy when the object falls. Elastic potential energy is possessed by objects that have been stretched or squashed but are able to regain their original shape when released. Elastic potential energy becomes kinetic energy on release. Nuclear potential energy is stored inside the nucleus of atoms. When atomic nuclei are split or joined together, a huge amount of energy is released as thermal energy, light and radiation. The radiation can cause health hazards. Chemical potential energy is energy stored in the bonds that hold atoms together. Many substances have energy-rich bonds and, given the right conditions, this energy can be released as infrared or light or sound energy. Magnetic potential energy can be stored in certain metal objects held in a magnetic field. A magnet will change the orientation of a compass needle, but when the compass is moved away, the needle will swing back to its original position.

object possess move different stored stored potential 'active energy' Radiant Sound vibrations Kinetic moving mass fast Thermal matter thermal faster thermal rise charged conductor electrons seen Gravitational potential gravitational kinetic Elastic potential kinetic Chemical energy light sound Magnetic magnet