Standards of Measurement
Standards Covered
PS-1.3 Use scientific instruments to record
measurement data in appropriate metric units
that reflect the precision and accuracy of each
particular instrument
PS-1.5 Organize and interpret data from a
controlled scientific investigation by using
mathematics (including formulas and
dimensional analysis), graphs, models, and/or
technology
Units and Standards
• Standard – an exact quantity that people
agree to use for comparison to represent a
measurement or some other quality
• Le Systeme Internationale d’Unites, SI System,
is the system used by scientists and the rest
of the world to make measurements
– Each type of measurement has a base unit
– Each base unit has a standard
– Prefixes used with base units that are based on
multiples of ten
Length
Metric Units
Length: The distance from point to point.
The basic unit of length in the SI system is the meter and is
represented by a lowercase m.
Standard: The distance traveled by light in absolute vacuum in
1⁄299,792,458 of a second.
Measured using a metric ruler or a meter stick.
Metric Units
1 Kilometer (km) = 1000 meters
1 Meter = 100 Centimeters (cm)
1 Meter = 1000 Millimeters (mm)
Which is larger?
A. 1 meter or 105 centimeters C. 12 centimeters or 102 millimeters
B. 4 kilometers or 4400 meters D. 1200 millimeters or 1 meter
English vs. Metric Units
Which is longer?
A. 1 mile or 1 kilometer
B. 1 yard or 1 meter
1 mile
1.6 kilometers
C. 1 inch or 1 centimeter
1 inch = 2.54 centimeters
1 yard = 0.9444 meters
Left Image: http://webapps.lsa.umich.edu/physics/demolab/controls/imagedemosm.aspx?picid=1167
Right Image: http://share.lancealan.com/N800%20ruler.jpg
How to Read a Metric Ruler
The large lines are the cm
The small lines in between are the millimeters
- Notice there are 10 mm in 1 cm
1) Line up one edge of what you
are measuring, with the zero
mark on the ruler
2) Read all the known digits in the
measurement, then estimate
ONE place value past the known
digits…
‘Tell what you know… then
estimate one number further.’
Measuring Length
How many millimeters are in 1
centimeter?
1 centimeter = 10 millimeters
2.80
What is the length of the line in centimeters? _______cm
28.0
What is the length of the line in millimeters? _______mm
Ruler: http://www.k12math.com/math-concepts/measurement/ruler-cm.jpg
A
43.5 mm
4.35 cm
60.6 mm
6.06 cm
B
C
8.5 mm
0.85 cm
30.0 mm
3.00 cm
D
Volume
Metric Units
Volume is the amount of space an
object takes up.
The base unit of volume in the
metric system is the liter (L or l) for
liquids and cubic centimeter (cm3)
for solid objects.
Standard: 1 liter is equal to
one cubic decimeter
Metric Units
1 liter (L) = 1000 milliliters (mL)
1 milliliter (mL) = 1 cm3 (or cc)
= 1 gram*
Measured using a Graduated
Cylinder
Which is larger?
A. 1 liter or 1500 milliliters
B. 200 milliliters or 1.2 liters
C. 12 cm3 or 1.2 milliliters*
* When referring to water
Liter Image: http://www.dmturner.org/Teacher/Pictures/liter.gif
English vs. Metric Units
Which is larger?
1 fl oz = 29.573 ml
A. 1 liter or 1 gallon
1 12-oz can of
soda would equal
approximately 355
ml.
B. 1 liter or 1 quart
C. 1 milliliter or 1 fluid ounce
1 quart = 0.946 liters
1 gallon = 3.79 liters
It would take approximately
3 ¾ 1-liter bottles to equal a
gallon.
Measuring Volume
We will be using graduated cylinders
to find the volume of liquids and
other objects.
Read the measurement based on the bottom
of the meniscus or curve. When using a real
cylinder, make sure you are eye-level with the
level of the water.
What is the volume of water in the cylinder?
_____mL
43.0
What causes the meniscus?
A concave meniscus occurs when the molecules of the liquid attract
those of the container. The glass attracts the water on the sides.
Top Image: http://www.tea.state.tx.us/student.assessment/resources/online/2006/grade8/science/images/20graphicaa.gif
Bottom Image: http://morrisonlabs.com/meniscus.htm
What is the volume of water in each cylinder?
37.0 mL
52.0 mL
23.0 mL
Pay attention to the scales for each cylinder.
Images created at http://www.standards.dfes.gov.uk/primaryframework/downloads/SWF/measuring_cylinder.swf
Measuring Liquid Volume
Measuring Solid Volume
9 cm
We can measure the volume of a regular
object using the formula:
length x width x height.
8 cm
_____
_____
10cm X _____
8cm X _____
9cm = 720
cm3
10 cm
We can measure the volume of
irregular object using:
water displacement.
mL
Amount of H2O with object =260
______
mL
About of H2O without object =200
______
60 mL =60
cm3
Difference = Volume = ______
______
Mass
Metric Units
Mass refers to the amount of matter in an object.
The base unit of mass in the metric system in the
kilogram and is represented by kg.
Standard: 1 kilogram is equal to the mass of the
International Prototype Kilogram (IPK), a platinumiridium cylinder kept by the BIPM at Sèvres, France.
Mass is measured using a triple beam balance.
Kilogram Prototype
Metric Units
1 Kilogram (km) = 1000 Grams (g)
1 Gram (g) = 1000 Milligrams (mg)
Which is larger?
A. 1 kilogram or 1500 grams C. 12 milligrams or 12 kilograms
B. 1200 milligrams or 1 gram D. 4 kilograms or 4500 grams
Kilogram Prototype Image - http://en.wikipedia.org/wiki/Kilogram
English vs. Metric Units
Which is larger?
1. 1 Pound or 100 Grams
1 pound = 453.6 grams
2. 1 Kilogram or 1 Pound
3. 1 Ounce or 1000 Milligrams
1 ounce of gold =
28,349.5 milligrams
100 kilogram =
220 pounds
Measuring Mass
We will be using triple-beam
balances to find the mass of
various objects.
To begin, you must ‘calibrate’ the
balance. The ‘weights’ are all
aligned to the far left… near the
tray… then you turn the knob under
the tray until you get the lines on the
right-side of the scale to match up.
Once you have calibrated the balance
and placed the ‘tares in their notches’,
you add up the amounts on each
beam to find the total mass.
What would be the mass of the object
measured in the picture?
373.35 g
70 + _______
3.35 = ________
300 + ______
_______
Top Image: http://www.southwestscales.com/Ohaus_Triple_Beam_750-SO.jpg
Bottom Image: http://www.regentsprep.org/Regents/biology/units/laboratory/graphics/triplebeambalance.jpg
Measuring Mass – Triple-Beam Balance
1st – Place the object on the balance, in the center of the tray.
2nd – Slide the large weight to the right until the arm drops
below the line. Move the tare back one notch. Make sure
it ‘locks’ into place.
3rd – Repeat this process with the top weight.
When the arm moves below the line, back it up
one notch.
4th – Slide the small
slider tare on the
front beam until the
lines match up.
5th – Add the amounts on each beam to find the total mass to the
nearest tenth of a gram, then estimate one number further.
137.45g
203.25g
43.05g
Time and
Temperature
Time - Interval between two events
The base unit of time is the second (s).
Standard: The frequency of the cesium-133 atom as the ‘reference clock’
Time is measured with a clock/ stop watch.
Temperature – “how hot or cold something is”
The base unit in the ‘old’ Metric system is degrees Celsius (˚C)
The base unit in the modern SI system is the Kelvin (K)
Standard: Based on freezing and boiling points of pure water at
standard temperature and pressure… (0˚C and 100˚C at 1atm)
Measured with a thermometer
°C + 273 = K
Thirty is HOT, Twenty is NICE,
Ten is CHILLY, and
Zero is ICE!!
Accuracy and
Precision
Scientific Data
• Accuracy – How close value is to accepted
value (control)
• Precision – how close repeated
measurements are to one another
– Determined by the measuring device
being used
– The smaller the Graduations… the more
Precise the measurement! And the more
likely it is to be repeated
SI Prefixes
Kilo (k) = 1000x
hecta (h) = 100x
deka (dk) = 10x
deci (d) = .1x or 1/10
centi (c) = .01x or 1/100
milli (m) = .001x or 1/1000
Standards Covered
PS- 1.2 Use appropriate laboratory
apparatuses, technology, and
techniques safely and accurately
when conducting a scientific
investigation.
PS- 1.9 Use appropriate safety
procedures when conducting
investigations.
A Special Relationship for Water
1 milliliter (ml) = 1 cubic centimeter (cm3) = 1 gram (g)
For Everything Else
1 milliliter (ml) = 1 cubic centimeter (cm3)
Solids - cm3
Liquids – ml
Gases – either one
DON’T FORGET YOUR UNITS!!
Measurement
Lab