Chemical Change A change that produces one or more new substances and may release energy. Chemical Property A second set of properties in all kinds of matter. Circuit A path that is made from an electrical current. Claws A sharp, usually slender, and curved nail on the toe of an animal.
Originally, sandglasses were used as a measure for periods of time like the lamps or candles, but as clocks became more accurate they were used to calibrate sandglasses to measure specific periods of time, and to determine the duration of sermons, university lectures, and even periods of torture.
MEASURING ENERGY. Energy exists in many forms, so there are many ways to quantify it. Two of the most widely used for general purposes are the British Thermal Unit (BTU), which is a measure of energy content, and the watt, which is a measure of power, or how fast energy is used.