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Energy

Storing and transferring energy.

Everything stores energy. The more energy thing store, the more work they can do. The amount of energy stored is measured in Joules(J).

Energy cannot appear or disappear if anything changes, but some energy may spread from the energy stores to the surroundings.

Energy and chemistry.

Energy is not a physical substance. In a chemical reaction, the mass of chemicals before and after is the same, but the amount of energy stored in the chemicals changes. Some energy spreads to the surroundings, or may be absorbed from the surroundings.

Infrared radiation.

Emission absorption and uses.

All objects emit and absorb infrared radiation.

Shiny light coloured surfaces absorb infrared radiation slower than black matt surfaces. They reflect infrared radiation well.

Hotter surfaces emit radiation faster than cooler surfaces.

We can design objects to reduce the rate of energy transfer.

Black surfaces inside an oven emit infrared radiation better thin shiny surfaces. This hep heat to transfer to the food cooking inside the oven.

Objects are absorbing and emitting infrared radiation at the same time. If infrared radiation is emitted faster than it is absorbed, then the object cools down.

Infrared radiation and global warming.

Many things affect the rate of global warming. One theory is that the sea water is dark coloured and will absorb infrared radiation from the sun faster than ice does.

Kinetic theory.

Bonds between particles.

Bonds between particles are strongest in solids and weakest in gases.

Melting is when a solid changes to a liquid. When the solid is heated, particles vibrate more vigorously. Bonds between particles break and reform so particles can change places.

Freezing is when a liquid cools and changes to a solid.

Boiling is when a liquid changes to a gas when the liquid is heated. The particles break their bonds and an move around randomly.

Condensing is when a gas cools and changes to a liquid.

Particles.