NATS 1815 A Fall 25 Lecture One: Measurement Standards and Significant Figures

Flashcards covering key vocabulary from the lecture on standards of length, mass, and time, powers of 10, unit conversions, and significant figures.

Standards in measurement

Criteria that measurements must meet: readily accessible, possess a reliably measurable property, yield the same result, and not change with time.

Length (m)

A fundamental unit of distance, measured in meters, with scales ranging from subatomic particles to cosmic distances.

One light-year

A unit of astronomical distance, equal to 9.46 × 10^15 meters.

Mass (kg)

A fundamental unit representing the amount of matter in an object, measured in kilograms, with scales from electrons to the observable Universe.

Time Interval (s)

A fundamental unit measuring the duration of events, expressed in seconds, spanning from nuclear collisions to the age of the Universe.

Yocto (y)

A prefix representing 10^-24.

Zepto (z)

A prefix representing 10^-21.

Femto (f)

A prefix representing 10^-15.

Nano (n)

A prefix representing 10^-9.

Micro (µ)

A prefix representing 10^-6.

Milli (m)

A prefix representing 10^-3.

Kilo (k)

A prefix representing 10^3.

Mega (M)

A prefix representing 10^6.

Giga (G)

A prefix representing 10^9.

Tera (T)

A prefix representing 10^12.

Exa (E)

A prefix representing 10^18.

Yotta (Y)

A prefix representing 10^24.

Unit Conversion

The process of changing a measurement from one unit to another using appropriate conversion factors, such as converting inches to centimeters.

Order-of-Magnitude Calculation

An estimation process that approximates a quantity to the nearest power of 10.

Significant Figures

The digits in a measurement that carry meaning and contribute to its precision, indicating the reliability of the measurement.

Significant Figures (Multiplication/Division Rule)

When multiplying or dividing quantities, the final answer's number of significant figures should match the quantity with the fewest significant figures.

Significant Figures (Addition/Subtraction Rule)

When adding or subtracting quantities, the final answer's number of decimal places should match the quantity with the smallest number of decimal places.

Rounding (last digit dropped > 5)

If the last digit dropped is greater than 5, the last retained digit is increased by 1 (e.g., 1.346 rounds to 1.35).

Rounding (last digit dropped = 5)

If the last digit dropped is exactly 5, the last retained digit is rounded to the nearest even number (e.g., 1.345 rounds to 1.34, 1.335 rounds to 1.34).

Rounding (last digit dropped < 5)

If the last digit dropped is less than 5, the last retained digit is left as is (e.g., 1.343 rounds to 1.34).