Units & Measurements

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Units & Measurements

Measurements are an essential part of our daily lives. The three most common quantities that everyone knows, and measures, are length, mass and time. Physics experiments involve measuring, as accurately as possible, a variety of such quantities, which are technically called physical quantities.

When we measure such a quantity, we always compare it with some reference standard. Such a standard defines a unit of the quantity. Any measurement will always consist of two parts—a number and a unit—together describing the measure of that physical quantity.

A very important aspect of any measurement system is that of a common understanding of what, and how much, the units stand for. This requires the development and adoption of a set of unit measurement standards.

The system of units used by scientists and engineers around the world is commonly called the metric system, but since 1960 has been known officially designated as the International System, or SI system. Some other systems of units are the CGS (centimeter, gram, second) and the FPS (foot, pound, second) systems.

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