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

B. 4 kilometers or 4400 meters

C. 12 centimeters or 102 millimeters

D. 1200 millimeters or 1 meter

English vs. Metric Units

Left Image: http://webapps.lsa.umich.edu/physics/demolab/controls/imagedemosm.aspx?picid=1167Right Image: http://share.lancealan.com/N800%20ruler.jpg

Which is longer?

A. 1 mile or 1 kilometer

B. 1 yard or 1 meter

C. 1 inch or 1 centimeter

1.6 kilometers

1 mile

1 yard = 0.9444 meters

1 inch = 2.54 centimeters

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

Ruler: http://www.k12math.com/math-concepts/measurement/ruler-cm.jpg

How many millimeters are in 1 centimeter?

What is the length of the line in centimeters? _______cm

What is the length of the line in millimeters? _______mm

1 centimeter = 10 millimeters

2.80

28.0

43.5 mm 4.35 cm

60.6 mm 6.06 cm

A

B

8.5 mm 0.85 cm

30.0 mm 3.00 cm

C

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

Measured using a Graduated Cylinder

Metric Units

1 liter (L) = 1000 milliliters (mL)

1 milliliter (mL) = 1 cm3 (or cc) = 1 gram*

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 waterLiter Image: http://www.dmturner.org/Teacher/Pictures/liter.gif

English vs. Metric Units

Which is larger?

A. 1 liter or 1 gallon

B. 1 liter or 1 quart

C. 1 milliliter or 1 fluid ounce

1 gallon = 3.79 liters

It would take approximately 3 ¾ 1-liter bottles to equal

a gallon.

1 fl oz = 29.573 ml1 12-oz can of soda would equal

approximately 355 ml.

1 quart = 0.946 liters

Measuring Volume

Top Image: http://www.tea.state.tx.us/student.assessment/resources/online/2006/grade8/science/images/20graphicaa.gifBottom Image: http://morrisonlabs.com/meniscus.htm

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

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.

43.0

Measuring Liquid Volume

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Pay attention to the scales for each cylinder.

52.0 mL

37.0 mL

23.0 mL

Measuring Solid Volume

10 cm

9 cm

8 cm

We can measure the volume of a regular object using the formula:

length x width x height.

_____ X _____ X _____ = _____

We can measure the volume of irregular object using:

water displacement.

Amount of H2O with object = ______

About of H2O without object = ______

Difference = Volume = ______ = ______

10cm 8cm 9cm 720 cm3

260 mL

200 mL

60 mL 60 cm3

Mass

Metric UnitsMass 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 platinum-iridium cylinder kept by the BIPM at Sèvres, France.

Mass is measured using a triple beam balance.Metric Units

1 Kilogram (km) = 1000 Grams (g)

1 Gram (g) = 1000 Milligrams (mg)

Which is larger?

A. 1 kilogram or 1500 grams

B. 1200 milligrams or 1 gram

C. 12 milligrams or 12 kilograms

D. 4 kilograms or 4500 grams

Kilogram Prototype

Kilogram Prototype Image - http://en.wikipedia.org/wiki/Kilogram

English vs. Metric Units

Which is larger?

1. 1 Pound or 100 Grams

2. 1 Kilogram or 1 Pound

3. 1 Ounce or 1000 Milligrams

1 pound = 453.6 grams

100 kilogram = 220 pounds

1 ounce of gold = 28,349.5 milligrams

Measuring Mass

Top Image: http://www.southwestscales.com/Ohaus_Triple_Beam_750-SO.jpgBottom Image: http://www.regentsprep.org/Regents/biology/units/laboratory/graphics/triplebeambalance.jpg

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?

_______ + ______ + _______ = ________ g300 70 3.35 373.35

Measuring Mass – Triple-Beam Balance1st – 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) = 1000xhecta (h) = 100xdeka (dk) = 10x

deci (d) = .1x or 1/10centi (c) = .01x or 1/100milli (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 Water1 milliliter (ml) = 1 cubic centimeter (cm3) = 1 gram

(g)

For Everything Else1 milliliter (ml) = 1 cubic centimeter (cm3)

Solids - cm3

Liquids – mlGases – either one

DON’T FORGET YOUR UNITS!!

MeasurementLab