Hon Physical Science 9th grade mod 1

What is science?

a process based on inquiry, that helps develop explanations about events in nature

experiment

tests the effect of one thing on another using a control

variable

quantity that can have more than a single value

independent variable

causes a change in the dependent variable (manipulated, plotted on x-axis)

dependent variable

changes in response to the independent variable (responding, plotted on y-axis)

constant

factor that does not change

control

standard by which test results can be compared

bias

can occur when a scientist’s expectations change how the results are analyzed or conclusions are formed

ex: positive test result to promote a product & ignoring negative results

scientific theory

well-tested explanation for a set of observations or experimental results

scientific law

statement (rule) summarizing patterns in nature without attempting to explain it

qualitative data

uses words to describe data

quantitative data

uses numbers to describe data

standard

exact quantity that people agree to use to compare measurements

measurement

dimensions, capacity, or amount of something

English system

inches, feet, gallons, pounds

Metric system

based on multiples of ten & used by most nations

SI units

International System of Units - a version of the metric system accepted universally

base units

are based on universal physical constants

derived units

unit made by combining other SI units

ex: m/s, m2, kg/m3

scientific notation

a way of expressing a value as a product of a number between 1 and 10 and a power of 10

SI prefixes

used in combination with base unit to indicate powers of ten

Unit Conversions

dimensional analysis can be used for conversions within a metric system and from metric to English

precision

how close a set of measurements are to one another, also a gauge of how exact a measurement is, limited by the measuring tool

accuracy

closeness of a measurement to the accepted value

significant figures

all digits that are known in a measurement plus one digit that is estimated

rules for sig. figs

all nonzero digits are sig.

final zeros after a decimal point are sig.

zeros between two other sig. figs. are sig.

zeros that are placeholders are NOT sig.