Standard-and-Units.pdf

STANDARDS AND UNITS SI Units Scientific Notations Accuracy and Precision Significant Figures Branches of Physics Physical Quantities We use a number to describe a physical phenomenon quantitatively and this number is called physical quantity. In physics, physical quanti...

STANDARDS AND UNITS SI Units Scientific Notations Accuracy and Precision Significant Figures Branches of Physics Physical Quantities We use a number to describe a physical phenomenon quantitatively and this number is called physical quantity. In physics, physical quantities are expressed in terms of units of measurement which are defined by standards. These standards are listed in the metric system, officially termed as International Standard or Systéme International (SI). SI Units: Fundamental and Derived Units In physics, there are seven fundamental physical quantities that are measured in base or physical fundamental units: length, mass, time, electric current temperature, amount of substance, and luminous intensity. Units for other physical quantities (such as force, speed, and electric charge) described by mathematically combining these seven base units. I Quantity Unit Symbol Definition Length meter m This is distance travelled by light in a vacuum in 1/299,792,458 second. It is the actual mass of platinum-iridium cylinder kept at the International Bureau of Mass kilogram kg Weights and Measures in Sévres, France. This refers to the duration for 9,192,631,770 cycles of the microwave radiation Time second s corresponding to the transition between two lowest states of cesium atom. Temperature Kelvin K It means fraction of 1/273.16 of the triple point of water. This is the constant current flowing in each of two long parallel wires, 1.0m apart, Eclectic Ampere A that produce between these wires a force equal to newton per meter length of each Current wire Amount of It refers to amount of substance that contains as many atoms or molecules as there Mole mol substance are atoms in 0.012 kg of carbon-12. One candela is the luminous intensity in a given direction of a source that emits a Luminous candela cd monochromatic radiation of frequency Hz and that has a radiant intensity in that intensity direction of 1/683 watts per steridian. Metric Prefixes Unit Conversion and Dimensional Analysis A co n ve r s i o n f a ct o r i s a r a t i o expressing how many of one unit are equal to another unit. Using Scientific Notation with Physical Measurements Scientific notation is a special way of representing numbers which are too large or small in a unique way that makes it easier to remember and compare them. They are expressed in the form (a × 10n). Here ‘a’ is the coefficient, and ‘n’ is the power or exponent of the base 10. Rules in Scientific Notation Express the following numbers in scientific notation. 1) 0.0026 2) 0.0000401 3) 643.9 4) 816 5) 45800 Transform the following scientific notation to standard notation Seatwork:  Seatwork: Solve each problem and show your complete solution. Write your answer on a 1 whole sheet. (Pairwork)