Cornell Notes — Full Topic (Units, Measurements & Errors) — Notes

Cue / Question	Notes
What are the 7 SI base units?	metre (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol), candela (cd)
Dimensional formula of force?	[ $M^{1}$ $L^{1}$ $T^{-2}$ ] — Newton = kg m $s^{-2}$
Dimensional formula of energy?	[ $M^{1}$ $L^{2}$ $T^{-2}$ ] — Joule = kg $m^{2}$ $s^{-2}$
Dimensional formula of pressure?	[ $M^{1}$ $L^{-1}$ $T^{-2}$ ] — Pascal = kg $m^{-1}$ $s^{-2}$
Dimensional formula of power?	[ $M^{1}$ $L^{2}$ $T^{-3}$ ] — Watt = kg $m^{2}$ $s^{-3}$
Dimensional formula of angular momentum?	[ $M^{1}$ $L^{2}$ $T^{-1}$ ] — kg $m^{2}$ $s^{-1}$
Error rule for Z = A + B?	$\Delta Z$ = $\Delta A$ + $\Delta B$ (absolute errors add)
Error rule for Z = A × B?	$\Delta Z$ /Z = $\Delta A$ /A + $\Delta B$ /B (relative errors add)
Error rule for Z = Aⁿ?	$\Delta Z$ /Z = n × ( $\Delta A$ /A)
Two limitations of dimensional analysis?	(1) Cannot find dimensionless constants; (2) Cannot distinguish between formulas with same dimensions
Significant figures: leading zeros?	Never significant — 0.00450 has 3 sig figs
Significant figures: trailing zeros after decimal?	Always significant — 2.300 has 4 sig figs

Summary: Units, Measurements & Errors is a NEET foundation topic. Every physical quantity is expressed using 7 SI base units. Dimensional analysis lets you check equations, derive formulas, and convert units — but cannot determine dimensionless constants. Error propagation rules: absolute errors add for sums/differences; relative errors add for products/quotients; for a power Aⁿ, multiply relative error by n. Significant figures track measurement precision: leading zeros are never significant, trailing zeros after a decimal always are.