how do people gather scientific information?. scientific method i’m tad identify a problem make a...
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How do people gather scientific information?
Scientific MethodI’M TADIdentify a ProblemMake a HypothesisTest the Hypothesis (Perform an Experiment)Analyze the DataDraw Conclusions
Sometimes a 6th step is included in which you share your conclusions with others
Hypothesis vs. Theory vs. LawHypothesis – An educated guess
Scientific Theory – A hypothesis supported by many experiments
Scientific Law - facts of nature accepted as truth
Controlled ExperimentsA Controlled Experment is one where only
one variable is tested at a time
Why is it important to use controlled experiments?
Controlled ExperimentsControl Group – the group that doesn’t
receive the experimental treatment, a standard for comparison
Independent Variable – the variable in the experiment you change
Dependent Variable – the variable in the experiment that only changes because you changed the independent variable
Controlled ExperimentsExample:
Merck decides to test a new antibiotic to see if it will cure patients’ sinus infections. Some testers are given pills containing the new antibiotic and others are given a placebo, or sugar pill.
Identify:ControlIndependent VariableDependent Variable
The Metric SystemIn the US, we use the English system of units
(lbs, in., oz., etc.)The rest of the world, including the scientific
world, uses the SI (Systeme Internationale) or Metric System
Why?It’s universal (used everywhere but US)Units are converted based on factors of 10
SI UnitsWhat are the SI base units for these
measurements?
Length/distance?Meter (m)
Volume?Liter (L)
Time?Seconds (s)
SI UnitsWhat are the SI base units for these
measurements?
Temperature?Kelvin (K), the absolute scale for Celsius (°C)
Mass?Grams (g)?We use grams for the base unit, but kilograms
(kg) are considered the SI unit for mass
Metric ConversionsWe use SI units because it’s easy to convert
between magnitudesWe use a prefix to identify the magnitude of
the measurementExamples: kg, cm, mL
To remember the prefixes, use the mnemonic:
King Henry Died by Drinking Chocolate Milk
Metric PrefixesPrefix Symbol Magnitude
Kilo k 1,000(103)
Hecto h 100 (102)
Deca da 10 (101)
base unit g, L, m 1 (100)
Deci d 0.1 (10-1)
Centi c 0.01 (10-2)
Milli m 0.001 (10-3)
Converting between Metric UnitsTo convert between metric units, count how
many spaces are between the unitsMove the decimal point that many spaces in
the direction you counted towardsExample 1: 10m = ? cm
Answer: 1,000cmExample 2: 10mL = ? hL
Answer: 0.0001hLkilo hecto deca base deci centi milli
DensityThe amount of matter in a given amount of
space is known as Density(D)D = m/VCommon units: g/mL, g/cm3
Note: 1mL = 1cm3
Example: If a 45.2g block has a volume of 11.6mL, what is it’s density?D = 45.2g/11.6mLD = 3.90g/mL
AreaA = l x wFor a square: A = side2
For a triangle: A= ½ bhCommon units: cm2, m2
Example: If a square has a length of 5cm and a width of 3cm, what is its area?A = 5cm x 3cmA = 15cm2
Matter, Mass and WeightMatter – anything with mass and volumeMass – the amount of matter in an objectWeight – the effect of gravity on an object
What is the difference between mass and weight?Gravity