List an example of things measured by mass, volume, and length.

Agenda for Wednesday Sept 24th 1. Go over test2. Measurement notes3. Measurement practice

Accuracy & Precision

• Accuracy:– Freedom form mistakes or errors;

Correctness

• Precision:– The ability to repeat; Repeatability

Units of Measurement• International System of Units (SI)

Quantity Base Unit Abbreviation

Length Meter m cm, mm, km

Mass Kilogram kg g, mg

Time Second s

Temperature Kelvin K **Celsius (C)

Linear Measurement (straight lines)

• Length, Width, Height

• Tool:

• Meter stick, ruler

• Base unit of measurement:• Meters (m)

Area• How much surface an object covers• Units:

– m2, cm2 , etc.• Formula:

– A = L x W

Volume• How much space an object takes up• Two types:

– Regular and irregular

• Regular solids are box like– Volume is found by measuring length, width, and

height

• The volume of irregular objects is found by water displacement

Volume (cont.)• Tool:

– Regular = ruler or meter stick – Irregular = graduated cylinder

• Units of measurement:– m3, cm3 (for solids) – L , ml (for liquids)

• 1cm3 = 1ml

Volume of Regular Objects• Boxes:

– V = L x W x H

• Spheres – Formula : V = 4/3 πr3

• Cylinder– Formula: V = πr2 h– *π = 3.14

Measuring spheres/circles

• Measure end to end– Use paper on edge of spheres

• Measured diameter we need radius– Radius = ½ diameter– So: if d = 10 then r = 5

How many decimals?

What is accuracy? Precision?

Agenda for Thursday Sept 25th 1. Go over test2. Measurement pre-lab3. Measurement lab

Volume lab• Rounding

– What was the smallest number of digits in any of my measurements?

– You would then round off your calculated value to the smallest number of digits in your measurements.

Example:

If L = 2.11 cm, W = 4.3212cm and H = 7.10cm, 7.10cm has the smallest number of digits so your calculated value would be rounded to three digits.

2.11 x 4.3212 x 7.10 = 64.735897 would be rounded to 64.7

Three students reported the length of a pencil to be 12 cm, 12.0 cm, and 12.00 cm. Do all three readings contain the same information? Which one has the most? Why?

Agenda for Friday Sept 26th 1. Measurement lab

How do you decide how much water is in the cylinder?How much water is there?

Agenda for Monday Sept 29th 1. Volume of Irregular objects

What is the volume of a box with the following dimensions:

Width = 3.45Length = 2.56Height = 1.89

Agenda for Tuesday Sept 30th 1. Finish Measurement notes2. Metric Conversion Notes3. Density

Mass• Definition:

– The amount of matter in an object• Tool:

– Triple beam Balance• Base unit:

– Grams (g) – A penny has the mass of about 1g

• 1g = 1cm3 for water only

Making a connection

• When you use water (this works only for water)

1 ml = 1 cm3 = 1 g

Weight• Definition:

– The gravitational pull on an object• Tool:

– Scale• Base unit:

– Newton (N)

Mass Vs. Weight

Temperature• Definition:

– Measurement of the average kinetic energy of molecules

• Tool: – Thermometer

• Base unit: – Celsius (co) and Kelvin (ko)

Density

• Def. – ratio of the mass of a substance to the volume of a substance– Formula: D = m/V

• Density = mass/volume

• Units: g/cm3

• Low density means atoms are not as packed together

Density

• Density determines whether an object will float or sink– Less dense objects float

• Water has a density of 1 g/cm3

• Use density to find substances– lab

Density Problems

• If 12.0 cm3 has a mass of 9.17 g, what is the density?

• If an object has a density of 4.2 g/cm3 and a mass of 30 g, what is its volume?

Explain how you would find the volume of an irregular shaped object.

Agenda for Monday Jan 13th 1. Finish notes2. Go over worksheet3. Mass lab

What is the difference between mass and weight?

Agenda for Tuesday Jan 14th 1. QUIZ2. Density3. Start lab

TEST TUESDAY

What is density?

Agenda for Wednesday Jan 15th 1. Demo2. Lab/worksheet