Energy

• There are many different forms or types of energy. These include:

  • kinetic energy
  • heat energy
  • light energy
  • chemical energy
  • elastic potential energy or strain energy
  • gravitational potential energy
  • electrical energy
  • magnetic energy
  • nuclear energy
• • Kinetic energy is the energy of a moving object

  All moving things have kinetic energy, even very large things like planets, and very small ones like atoms. The amount of kinetic energy an object has depends on:

  • the mass of the object
  • the speed of the object

  An object at rest (not moving) has zero kinetic energyv
• • Heat energy flows from hot objects to cold objects.

  A cup of tea “feels warm” because it is giving off heat energy. It is the hot object, you are the cold object. Sometimes heat energy is called thermal energy.
• • Elastic potential energy is stored in stretched or squashed materials.

  Some objects can change shape when they are pushed or pulled. Rubber balls, springs and elastic bands are like this. When an object is stretched or squashed, it stores elastic potential energy. The energy is released when it returns to its original shape and size.
• • Gravitational potential energy is the type of energy an object stores due to its height above the ground.

  When an object is lifted above the ground, or moved higher up, it gains gravitational potential energy. The amount of gravitational potential energy an object stores depends on:

  • the mass of the object
  • the height above the Earth’s surface
  • the gravitational field strength
• • Chemical energy is the energy stored in the bonds that connect atoms and molecules together.

  Chemical energy is the most widely used type of energy on Earth and is vital for our existence.

  Chemical energy is stored in the food we eat. As the bonds between the atoms in food break, a chemical reaction takes place and energy is released. We use this energy to keep us warm, to move, to climb stairs, to grow, when we sleep and many other things.

  Chemical energy is also stored in fuels such as coal, oil, natural gas, wood and peat.
• • Sound energy is the energy stored in a sound wave.

  Sound waves travel through solids, liquids and gases and are produced when an object vibrates like a plucked guitar string.
• • Light energy is a form of energy which our eyes can detect.

  Light is a form of electromagnetic radiation and can travel through a vacuum as well as through solids, liquids and gases. Light energy travels to us through space from the Sun. Green plants need light energy for photosynthesis to occur.
• • Electrical energy is a form of energy resulting from moving electric charges.

  Some objects carry electrical charges. These charged objects can exert forces on each other. Electrical energy can be seen in nature in a bolt of lightning which is a flow of charge through the air.
• • Magnetic energy is also a form of energy associated with moving charges

  Some objects can be magnetised and exert forces on other magnetised objects, or on magnetic materials.
• • Nuclear energy is stored in the nuclei of an atom

  Nuclear energy can be released by splitting heavy atoms or by fusing together two light atoms. Nuclear energy can be used to create electricity, but it must first be released from the atom. All the sun’s energy begins as nuclear energy.
• A very important law in physics is the Law of Conservation of Energy

  The Law of Conservation of Energy states that:

  • Energy can neither be created nor destroyed, but only changed from one form to another
• Energy resources are the different ways of supplying a particular form of energy

  For example:

  • Chemical energy is a form of energy.
  • Food, oil, coal, gas, petrol, turf and wood are some of the resources which supply chemical energy.
  • Kinetic energy is a form of energy.
  • Waves, tides, wind and falling water are some of the resources which supply kinetic energy.
• insulators are materials that do not allow the flow of electrons to pass through them
• conductors are materials that allow electricity to flow through them easily.
• convection: the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat