chapter 2, section 1
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This is the PowerPoint over our Nature of Science and Technology Book, Chapter 2, Section 1TRANSCRIPT
Measurement – A Common Language
Chapter 2, Section 1 – The Nature of Science and Technology
A Standard Measurement System
The Metric System› A system of measurement based on the
number 10
The International System of Units (SI)› Using SI allows scientists to compare data
and communicate with each other about their results
LENGTH The basic unit of length in
the SI system is the meter To measure objects smaller
than a meter scientists use units called the centimeter (cm) or the millimeter (mm)
Large distances are measured using kilometers (km)
To measure length we use a metric ruler
MASS The basic unit of mass in the SI system
is the kilogram (kg) To measure the mass of smaller objects
we use the gram (g) Even smaller masses are measured in
milligrams (mg) To measure mass we use a balance
MASS VS. WEIGHT…
Weight is the force of gravity acting on an object. This CAN change
Mass is the measure of the amount of matter an object contains. This ALWAYS stays the same!!
VOLUME
The amount of space an object takes up
To measure the volume of liquid scientists use the liter (L)
Smaller volumes are measured using milliliters (mL)
Volume of Liquids
To measure the volume of liquid just pour it into a container with markings that show the volume
Be sure you read the volume at the BOTTOM of the meniscus (the curved upper surface of a liquid in a column of liquid)
Volume of Rectangular Solids
To measure the volume of solid we use the cubic centimeter (cm3)
Larger volumes can be measured using the cubic meter (m3)
Calculate the volume using the formula: Volume=Length X Width X Height (or V=LWH)
Volume of Irregular Solids
To measure the volume of solid such as rock we can immerse the object in water and measure how much the water rises
Density
Density is the measure of how much mass is contained in a given volume
To calculate density divide the mass of the object by it’s volume (D=M/V)
Density is always expressed using TWO units such as grams per cubic centimeter (g/cm3), or grams per milliliter (g/mL)
Time
The SI unit of time is the second
The second can be divided, just as other units can (example, millisecond=one-thousandth of a second
Longer times are measured in minutes or hours
Temperature
Scientist commonly use the Celsius scale
On this scale water freezes at 0oC and boils at 100oC
Scientist may also use the OFFICIAL SI unit, Kelvin (K)
On Kelvin water freezes at 273oK and boils at 373oK
Measure temperature using a thermometer