Quantities {extensive quantity}| can be sums or differences over time or space ranges. They are total amounts: distance, area, volume, time interval, moles, energy, heat, entropy, charge, and mass. They have magnitude but no direction. Measuring extensive quantities requires accumulation. Extensive quantities are intensive-quantity integrals.
Quantities {intensive quantity}| can be values at times and places. They are instantaneous or local amounts, amount changes, or measurement ratios. Temperature, time, rate, concentration, and chemical potential are scalar magnitudes, with no direction. Distance, direction, velocity, acceleration, force, pressure, momentum, and intensity are vector quantities, with magnitude and direction. Intensive quantities can be matrices. Measuring intensive quantities requires comparing two points over time or distance, to make an extensive quantity. Intensive quantities are extensive-quantity differentials. For example, thermometers measure temperature by linearly expanding mass.
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Date Modified: 2022.0225