Unit 1: Scientific Data and Measurement

Scientific Method

A logical, systematic approach to the solution of a scientific problem

Control Group

remains constant

Independent Variable

- variable that is changed on purpose
- X axis

Dependent Variable

- a variable whose value depends on that of another
- Y axis

Qualitative

A description and observation

Quantitative

- A numerical number
- Found by measurement or mathematically solved

Accuracy

Closeness of measurement ​to correct/accepted value

Precision

Closeness of a set of measurements of the same quantity made in the same way

Taking Measurements Basics

- Numbers are only as accurate as the least precise measurement tool used
- The number of digits that can be measured with certainty PLUS one additional digit that is estimated

Theories

Broad generalization that explains facts or phenomena

Models

Explanation of how phenomena, data or events are related

SI Measurement System

- SI=System International
- Set of standards used by scientists everywhere
- Also called metric system
- Easily changed by changing the prefix

Derived Units

- Come from more than 1 measurement
- Treat units like numbers in math

Dimensional Analysis

Changing 1 unit into another using conversion
factor ratios
1. Start with the given
2. Think of the end
3. Connect the path
(Unit on top must match the bottom)

Percent Error

the percent that a measured value differs from the accepted value

Multiplying/Dividing Significant Figures

Answer has as many sig figs as the least significant measurement

Adding/Subtracting Significant Figures

Answer has as many decimal places as the least significant measurement

Scientific Notation

- A method of writing or displaying numbers in terms of a decimal number between 1 and 10 multiplied by a power of 10.
- #s listed are the only SIG FIGs
- Form is M x 10ⁿ

Inversely Proportional

A relationship when one variable goes up, another goes down. (Opposites)

Directly Proportional

A relationship when one variable goes up, another goes up.
(Same)