Units of Measurement and Sig Figs

Flashcards for reviewing units of measurement and significant figures.

Units of Measurement

Standard quantities used to express the magnitude of physical quantities (e.g., mm, m, ft).

Importance of Units

Units help understand physical meaning, calculate quantities, and identify errors in calculations.

Specific Heat

The amount of heat required to raise the temperature of a substance (e.g., Aluminum) by a certain amount, measured in J/g°C.

SI Base Units

The fundamental units in the International System of Units, including moles (amount), meters (distance), seconds (time), kilograms (mass), candela (luminosity), Kelvin (temperature), and Ampere (electric current).

Precision

The degree to which repeated measurements show the same result.

Accuracy

The degree of closeness of measurements to the actual or accepted value.

Uncertainty in Measurement

The range of possible values within which the true value of a measurement lies, including certain and uncertain digits.

Random Errors

Errors in measurement that cause values to be either larger or smaller; unavoidable but can be minimized.

Systematic Errors

Errors in measurement that consistently make values either larger or smaller; harder to recognize but can be minimized by calibration.

Significant Figures

The digits in a number that are known with certainty plus one final digit that is uncertain.

Exact Numbers

Values that have no uncertainty, such as defined values and quantities (e.g., 12 in = 1 foot, number of trials).

Rules for Significant Figures

Rules to determine which digits in a number are significant (e.g., non-zero digits are significant, zeros between non-zero numbers are significant).

Pacific-Atlantic Method

A method to determine significant figures based on the presence or absence of a decimal point.

Rounding Rules

Rules for rounding numbers based on the digit to be removed (e.g., round up if the digit is > 5, round down if < 5, round to the nearest even number if = 5).

Operations with Sig Figs: Addition and Subtraction

The answer will have the same number of decimal places as the number with the fewest decimal places.

Operations with Sig Figs: Multiplication and Division

The answer will have the same number of significant figures as the number with the fewest significant figures.

Combining Operations with Sig Figs

Don’t round in the intermediate steps; consider the number of sig figs at each step and only round the final answer.

Steps for Dimensional Analysis

Convert using equivalence statements, derive unit factors, and multiply to obtain the desired units.