Scientific method and si units
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Transcript of Scientific method and si units
Scientific Method
Scientific Method
Systematic approach used in scientific studies
A logical approach to solving problems by observing and collecting data, formulating a hypothesis, testing a hypothesis, and formulating theories that are supported by data
Steps of the Scientific Method
• Observation • Problem Statement • Hypothesis Statement • Experiment / Data Collection • Conclusion Statement
Steps of the Scientific Method
Types of Observation
Qualitative Data and observations (QL) Color, shape, odor, or other physical
characteristics Quantitative Data and observations
(QN) Numerical information such as
temperature, pressure, volume, the quantity of a chemical formed
(PS)
Variable What does variable mean? To change…
Variables Independent Variable (IV)
aka manipulated variable Only ONE!!! The one the INDividual (YOU) physically change/manipulate
Dependent Variable (DV) aka the responding variable Only ONE!!! The one that changes (or you hope will change) when you change the IV The one you are collecting data about/measuring
Constant Variables MANY of these All the things you want to keep the SAME (do NOT change)
Variables
You should be able to identify the IV and DV from your PS!!!!
Formula:
If…(state what will be done to the IV), then…(state what is predicted to happen to the DV)
CLASS WORKName That Variable!
Control (1):Constants(2) :
Independent (1): Dependent (1):Hypotheses (1):
1. An experiment that tests how quickly different temperatures will dissolve sugar cubes.
2. An experiment that explores how different colors of light impact plant growth.
3. How does the temperature of a chemical reaction change over time?
Experiment a planned way to test a hypothesis and find out
the answer to the problem statement. a way to collect data and determine the value of
the DV. compares the IV to the DV. can only test one DV at a time and change one
IV at a time
Experiment Variables Materials and Procedures Data and Results Section Include observations (QL and QN) Pictures/tables/graphs/calculations
Why Do We Use Graphs? Graphs help us visualize
numerical data. •There are several different
types of graphs: Bar graphs: compare multiple
objects Pie graphs: shows relationships
of parts to a whole Line graphs: show the
relationship between 2 variable
Types of Relationships (between variables)
Direct: as x increases y increases
Indirect: as x increases y decreases
Constant: as x increases y remains the same
Conclusion Statement Do NOT use 1st person
Me, my, I, we, our, etc… VERY Objective
a summarization that presents the findings of the experiment, what the data shows, and states if the hypothesis was correct (supported) or incorrect (negated)
Restate PS Restate HYP Summarize M&P Analyze and explain data/results (tables, observations, pictures) State whether HYP was correct or not and EXPLAIN why Explain possible errors Explain ways to improve experiment/research Explain APPLICATION to biology and society
After we accept a hypothesis, experiment, and draw a conclusion… Many conclusions that support each other make
up a THEORY Explanation supported by many, many conclusions Many conclusions that support each other over a period
of time Atomic Theory Theory of Relativity CAN be DISPROVEN “The world is flat”
SCIENTIFIC LAW A relationship in nature that is supported by many, many
experiments No exceptions Law of Gravity
SI Units
In science, we need to speak the same language
1795 French scientists develop metric system
1960 International committee meets to
update the system and names it the “Systeme Internationale d’Unites” aka SI
SI Base Units
Seven SI base units Base unit
A defined unit in a system of measurement that is based on an object or event in the physical world
SI Derived Units
Not all quantities can be measured with base units
More than one base unit can be used Speed limit is measure in….
MPH Miles per hour
Which is a combo of what base units? Length and time
Derived Units
Common derived units we will use Speed
Base unit of length and base unit of time Meters/second
Volume 3 base units of length
Length x length x length 1 dm3 = 1 L
Density Mass/volume Ratio that compares mass of an object to its
volume g/cm3 or g/mL
Class Work!
Suppose a sample of aluminum is placed in a 25 mL- graduated cylinder containing 10.5 mL of water. The level of water rises 13.5 mL. Mass is 25 g. What is the density of the aluminum sample?
What is the volume of a sample that has a mass of 150 g and a density of 5 g/mL?
Prefixes Used with SI units
Kids Hate Doing Math Dittos Christmas Morning
King Henry Died Monday Drinking
Chocolate Milk
Temperature
SI unit? Kelvin
Our thermometers measure Celsius To convert from Celsius to Kelvin
0o C + 273 = 273 K To convert from Kelvin to Celsius
373 K - 273 = 100o C