PHYSICS AND MEASUREMENT

FUNDAMENTAL QUANTITIES SI units:  Time – second  Mass – Kilogram  Length – meter

TIME  Before 1967, a second was defined as (1/60)(1/60)(1/24) of a mean solar day. As this is based on the rotation of Earth, it is not universal.  Redefined as 9,192,631,770 times the period of vibration of radiation from the cesium-133 atom making use of the high precision atomic clock.

MASS  Defined by the mass of a specific platinum-iridium alloy cylinder kept at the International Bureau of Weights and Measures in France.  Established in 1887  Duplicate at the National Institute of Standards and Technology in Gaithersburg, MD.

LENGTH  A meter is the distance traveled by light in a vacuum during a time of 1/299,792,458 second. (1983)  Originally defined as one ten-millionth of the distance from the equator to the North Pole along a longitudinal line that passes through Paris. (1799, earth-based)  Until 1960, distance between to marks on a specific platinum-iridium bar.  Between , defined as 1,650, wavelengths of orange-red light emitted from a krypton-86 lamp.

PERCENT ERROR  Percent error is a way of comparing a calculation or a measurement to an exact, known value.

STANDARD DEVIATION

ADDING AND SUBTRACTING WITH STANDARD DEVIATION

MULTIPLYING AND DIVIDING WITH STANDARD DEVIATION

EXAMPLE CALCULATION

EXAMPLE CALCULATION CONT…