H1.01. 2022 Measurement Notes

CJC H1 PHYSICS LECTURE NOTES JC1 2022 1(1) 1 Measurement Main concept(s) 1. Physical quantities & SI units 2. Uses of SI base units 3. Estimation 4. Errors and Uncertainties 5. Vectors Learning Outcome(s) Candidates should be able to: (a) recall the following base quantities and their units: mass (kg), length (m), time (s), current (A), temperature (K), amount of substance (mol). (b) state that one mole of any substance contains 6.02 × 10 23 particles and use the Avogadro number NA = 6.02 × 1023 mol–1 (c) 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. (d) use SI base units to check homogeneity of physical equations. (e) 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) (f) 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). (g) make reasonable estimates of physical quantities included within the syllabus. (h) distinguish between scalar and vector quantities, and give examples of each (i) add and subtract coplanar vectors (j) represent a vector as two perpendicular components (k) show an understanding of the distinction between systematic errors (including zero errors) and random errors. (l) show an understanding of the distinction between precision and accuracy. (m) assess the uncertainty in a derived quantity by simple addition of actual, fractional or percentage uncertainties or by simple numerical substitution (a rigorous statistical treatment is not required). Introduction Physics is an experimental science in which measurements are made. Evidence from measurements is the ultimate authority in establishing physics theories. Precise measurements enable the checking of experimental data against theoretical prediction. Accurate measurements allow us to overcome the unreliability of our human s enses and for the purpose of standardisation. Precise measurements made possible many applications e.g. study of the structure of matter, from geophysics to astronomy, in the medical industry where development of measuring instruments provides data that ar e crucial in informing clinical decisions. In this chapter, you will not only learn concepts

CJC H1 PHYSICS LECTURE NOTES JC1 2022 1(2) associated with measurements , but also vectors to represent physics quantities, and enable us to compute quantities and solve problems. Essential Questions • Why is there a need for standards in measurements and how are the standards of measurements defined or established? • Why are uncertainties inherent in all measurements and how can uncertainties be reduced?