Chapter 3: Measuring and Calculating Flashcards

Vocabulary flashcards covering fundamental measuring and calculating terms, SI units, unit prefixes, measurement limitations, accuracy, precision, and significant digits.

Measurement

The comparison of an unknown quantity to a standard unit.

Dimension

A measurable property of matter, such as length, mass, volume, time, or electrical charge.

Unit

A defined quantity used to measure a dimension, representing 'one of something.'

Scale

A line of dimensional units used to measure quantities, which is calibrated by accurately subdividing it.

Calibrate

To accurately subdivide a measurement scale on an instrument.

Instrument

An artificial device that refines, extends, or substitutes for human senses when measuring.

Metric system

A decimal system of measurement in which different-sized units are related to each other by powers of ten.

Système International d'Unités (SI)

The standard metric system adopted in 1960 that is used by research scientists worldwide.

Base unit

One of seven fundamental units in the SI system that directly measures a basic dimension.

Derived unit

A unit of measurement created from combinations of SI base units for convenience.

Kilogram

The SI base unit for mass, originally defined as the mass of $1\,\text{dm}^3$ of water and represented by a platinum-iridium cylinder made in 1889.

Atomic mass unit (u)

A non-SI unit equal to $1/12$ the mass of one carbon-12 atom, with an experimental value of approximately $1.66 \times 10^{-27}\,\text{kg}$.

Conversion factor

A fraction composed of equivalent quantities in different units that equals 1, used to transform a measurement's units without changing its amount.

Bridge notation

A structured layout resembling a trestle bridge used for multiplying and dividing several measurements and conversion factors simultaneously.

Accuracy

A numerical or qualitative evaluation of how close a measured value is to the actual or accepted value.

Percent error

A quantitative measurement of accuracy calculated using the expression $\text{Percent error} = \frac{|\text{observed} - \text{accepted}|}{\text{accepted}} \times 100\%$.

Precision

A evaluation of how exact and repeatable a measurement is.

Analog instrument

A measuring device that displays values by comparing an object to a scale or using a pointer on a scale.

Digital instrument

A measuring device that displays measurements using numerical digits only.

Data

Any recorded observation, which can be descriptive or numerical.

Significant digits (SDs)

All the digits in a measured value known for certain plus one estimated digit.

Literal equations

Equations expressed primarily with letters representing constants and variables, such as the ideal-gas law $PV = nRT$.

Density

The ratio of mass to volume for a given substance, expressed by the formula $D = \frac{m}{V}$.

Mega- (M)

An SI prefix representing a factor of million ($10^6$).

Kilo- (k)

An SI prefix representing a factor of thousand ($10^3$).

Deci- (d)

An SI prefix representing a factor of tenth ($10^{-1}$).

Centi- (c)

An SI prefix representing a factor of hundredth ($10^{-2}$).

Milli- (m)

An SI prefix representing a factor of thousandth ($10^{-3}$).

Micro- (µ)

An SI prefix representing a factor of millionth ($10^{-6}$).

Nano- (n)

An SI prefix representing a factor of billionth ($10^{-9}$).