Understanding Physical Quantities and Units! br br Physical Quantities:br Measurable quantities like length, mass, time, and temperature.br Must have numerical magnitude and a unit of measurement.br br Base Quantities:br Fundamental quantities from which others are derived.br Include length, mass, time, temperature, light intensity, electric current, and amount of substance.br br Derived Quantities:br Expressed in terms of base quantities.br Include area, volume, velocity, acceleration, pressure, momentum, electric charge, etc.br br SI System:br Established during the 11th General Conference on Weights and Measures in Paris, 1968.br Known as the "Universal International System of Units" or SI system.br br Base Units:br Units used to measure base quantities.br Examples: meter, kilogram, second.br br Derived Units:br Units used to measure derived quantities.br Examples: meter per second (velocity), square meter (area), cubic meter (volume).