ASRJC Measurement Notes

ANDERSON SERANGOON JUNIOR COLLEGE PHYSICS 9749 / 8867 1-1 Additional Notes Topic 1: Measurement Content • Physical quantities and SI Units • Scalars and vectors • Errors and uncertainties Learning Outcomes: Candidates should be able to: Physical quantities and SI units: (a) recall the following base quantities and their SI units: mass (kg), length (m), time (s), current (A), temperature (K), amount of substance (mol) (b) express derived units as products or quotients of the base units and use the named units listed in ‘Summary of Key Quantities, Symbols and Units’ as appropriate. (c) use SI base units to check the homogeneity of physical equations (d) show an understanding of and use the conventions for labelling graph axes and table columns as set out in the ASE publication Signs, Symbols and Systematics (The ASE Companion to 16-19 Science, 2000*) (e) use the following prefixes and their symbols to indicate decimal sub -multiples or multiples of both base and derived units: pico (p), nano (n), micro ( μ), milli (m), centi (c), deci (d), kilo (k), mega (M), giga (G), tera (T) (f) make reasonable estimates of physical quantities included within the syllabus Scalars and vectors: (g) distinguish between scalar and vector quantities, and give examples of each (h) add and subtract coplanar vectors (i) represent a vector as two perpendicular components Errors and uncertainties: (j) show an understanding of the distinction between systematic errors (includin g zero error) and random errors (k) show an understanding of the distinction between precision and accuracy (l) assess the uncertainty in a derived quantity by addition of actual, fractional , percentage uncertainties or by numerical substitution (a rigorous statistical treatment is not required) * Swinfen, T.C., & Association for Science Education. (200). Signs, symbols and systematics: The ASE companion to 16 - 19 science, Hatfield, Herts: Association for Science Education Name: _______________________________ ( ) Class: 25 / ____

ANDERSON SERANGOON JUNIOR COLLEGE PHYSICS 9749 / 8867 1-2 Additional Notes A.1 Physical Quantities • Quantities that can be measured are known as physical quantities. A physical quantity consists of a numerical magnitude and a unit. For example, mass, m = 65.0 kg • A symbol may be used to represent a physical quantity. In the above example, the symbol “m” represents both the numerical magnitude and the unit. Hence, writing “Let the mass be m kilograms” is incorrect, and should be written as “Let the mass be m”. • A symbol divided by a unit represents a number. This is used in labelling of graph axes and for headings of table columns • Physical quantities can be classified into two categories: base quantities (see A.2) and derived quantities (see A.3). Consequently, units are also classified into two categories, base units