Week 1 - Definitions, SI Units

Define dimension

A physical quantity e.g. length, time, mass, temperature

Define a unit

A means of expressing dimensions e.g. meters, seconds, kilograms, degree celsius

Define a conversion factor

ratio of equivalent quantities in different units e.g 1h = 3600s, 1kg = 1000g, 1inch = 25.4mm

State the SI units and abbreviations for Mass, Length, Temperature, Electric Current, Amount of substance, Luminous intensity

Define a derived unit

Combination of SI base units e.g. speed = m/s

State all the common decimal prefixes

State the rules for sig figs regarding multiplication and division

• The answer contains the number of sig figs as the measurement with fewest sig figs

State the rules for sig figs regarding addition and subtraction

• The answer contains the number of sig figs as the measurement with fewest decimal places

Define precision

How close measurements are to each other

Define accuracy

How close a measurement is to the true value

Define a systematic error

Values that are all either higher or lower than their true values

Define a random error

Values that are higher or lower than true values despite the absence of a systematic error