Physics (Unit 1 - Kinetic Theory and Conduction)

Kinetic theory describes how atoms move in solids, liquids and gases.

The energy an object or particle has because of its movement is called its kinetic energy.

Kinetic energy can explain the three states of matter.

Solids have strong forces of attraction that hold the particles close together in a fixed, regular arrangement. The particles don't have much energy so they can only vibrate about their fixed positions.

Liquids have weaker forces of attraction between the particles. The particles are close together, but can move past each other and form irregular arrangements. They have more energy than the particles in a solid - they move in random directions at low speeds.

There are almost no forces of attraction between the particles. The particles have more energy than those in liquids and solids - they are free to move and travel in random directions and at high speeds.

Conduction of heat occurs mainly in liquids.

Conduction of heat energy is the process where vibrating particles pass on their extra kinetic energy to neighbouring particles.

The process continues throughout the solid and gradually some of the extra kinetic energy (or heat) is passed all the way through the solid, causing a rise in temperature at the other side of the solid. And hence an increase in the heat radiating from its surface.

Usually conduction is faster in denser solids, because the particles are closer together and so will collide more often and pass energy between them. Materials that have larger spaces between their particles conduct heat energy much more slowly - these materials are insulators.

Metals conduct so well because the electrons are free to move inside the metal.

Because the electrons can move freely, this is obviously a much faster way of transferring the energy through the metal than slowly passing it between jostling neighbouring atoms. This is why heat energy travels so fast through metals.

If a spade is left in the sun and you touch the metal part, it feels much hotter than the wooden handle. This is because the metal is hotter.

If a spade is left in the sun and you touch the metal part, it feels much hotter than the wooden handle.

IT ISN'T HOTTER - it just conducts the heat into your hand much quicker than the wood, so your hand heats up much quicker.