What is heat anyway?

Heat energy is higher in hotter things than colder ones.As a result, atoms or molecules move faster in hot things (red, right) than in cold things (blue, left). This is the kinetic theory of motion.


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What happens when something has no heat at all?

Photo: Ice may look cold but it"s an awful lot hotter than absolute zero.Picture by Erich Regehr courtesy of US Fish & Wildlife Service.

What"s the difference between heat and temperature?

Artwork: An iceberg is much colder than a cup of coffee but it contains more heat energy because it"s so much bigger.

How can we measure temperature?

How does heat travel?

When you place an iron bar in a fire, heat travels through the metal by conduction (red arrows).What causes this?.Atoms at the hot end move much more quickly because they are absorbed by heat from the fire. As they absorb the heat, they pass it along the bar, gradually warming it up. As a general rule, pure soaps have an alkaline pH range of 8 to 10, so phenolphthalein drops don't necessarily indicate the readiness of a soap to be used. A liquid soap with a pH of 8.1 will perform similarly to a liquid soap with a pH of 8.3 (which crosses the color indicator line for phenolphthalein drops).Thermograms (sometimes called thermographs) show that all objects radiate heat. Two photos of a rocket on a launch pad were taken with normal cameras (above) and infrared thermal cameras (below).The purple, blue, and black areas are the coldest; the red, yellow, and white areas are the hottest.Robert.Herbert, NASA/JPL-Caltech.

Why do some things take longer to heat up than others?

Material specific heat capacities are very different for everyday materials.Blue metals have low specific heat capacities: they conduct heat well and store it poorly, so they feel cold.