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# Measurement and Standards Study Guide

The Metric System uses the idea of mass for measuring the amount of material rather than weight. The English System uses the pound as a unit of weight, even though it is also a unit of force. Back to the beginning of Units and Measures. Area An area is a length multiplied by a length. (A l l as in the formula list.) An area is an amount of surface. Having sixty seconds in an hour and twenty-four hours in a day come about from the ease of producing mechanical clocks. (Is it time to switch to metric time? Consider ten hours in a day, one hundred minutes in an hour, and one hundred seconds in a minute. G/cc cu. Ft, gal, etc. Temperaturelsius or Kelvin C or K Fahrenheit or Rankine energoule ( m.p.) J foot-pound heat Q calorie ( m.p.) cal BTU (British Thermal Unit) concentration C gram/L, mol/L, Molar M gal or cu. Time units of more than a year are in a type of metric configuration because they are in multiples of ten (decades, centuries, millennia, etc). The dimension of time is messy for good reason. An acre is defined as 43,560 square feet, so in using the unit 'acre' in dimensional analysis, the definition can be used to relate the acre to other units. Notice the squaring of a unit of length. You could measure mass by an inertial massometer. Visualize a metal strip.