Terminal Velocity
Investigating Forces and Motion in our Universe
Expedition 1
The Quest for Exactness
Objectives
• To accomplish your expedition goal successfully, you will need to
Evaluate systems and standards of measurement.
• Use measurements to describe objects in your environment.
• Discover why SI units are critical for communication among scientists,
engineers, industrial partners, and societies.
• Explore how measurements derived from SI units can be used to further
describe your physical environment.
• Compare accuracy and precision when analyzing measurement results.
• Assess how technological advancements to measurement tools impact
society.
• A model is any representation of an object or event used to explain
the natural world.
• When a scientist or engineer collects data, the information is
generally first put into a data table
• Scientists use graphs to turn these raw numbers into a visual
representation. Common graphs include line, bar, and circle graphs.
• http://gated.jason.org/gated/digital_library/pages/DigitalLibraryReso
urceView.aspx?h=1&rpid=16330
• Measurement uses numbers to describe processes and events.
• Length – the distance between two points,
• Time – the interval between two events
• Mass – the amount of matter in
an object
• Temperature – the amount of
energy within a sample of
matter
• Electric current – the flow of
charges
• Amount of a substance – the
number of atoms or
molecules in a sample of
material, and
• Luminous intensity –
the measure of light
intensity coming from
a source.
• Metrology is the study
of measurement.
• Metrology is the study of measurement.
• An estimate is an approximate measurement of an object or event
The Metric System
• The Metric System is a base-ten system
• SI units are the current world standard for measurement. There are
seven basic SI units. They are the meter, kilogram , second, ampere,
kelvin, mole and candela.
• Each unit is used to measure a particular quantity
• Additionally, SI units can be combined to describe area, volume,
density, speed, and acceleration.
• Scientific prefixes allow us to reduce the number of zeros and make
the figures more manageable. For example, 54,500,000,000 meters =
54.5 giga-meters, and 400,000,000,000 meters = 400 gigameters
• Converting Metric Units
• When you are converting from
a big unit (like kilometers) to a
smaller unit (like millimeters),
you multiply.
• When you are converting from
a small unit (like millimeters)
to a larger unit (like
kilometers) you devide.
U.S.Customary Units- used in only 3
countries?
• The U.S. ______________, and ___________
• Derived units use more than one measurement at a time. Some
examples include area, volume, density, speed, acceleration, and
weight.
• Area is the size of the surface of a two-dimensional object.
• Volume is the amount of space something takes up.
• Your body displaces, or pushes out, an amount of water equal to the
volume of your body below the water line.
• Speed is the change in distance over time.
• Accelleration is the rate of the change in velocity.
• Weight is the force exerted on any object with mass by the
gravitational acceleration of a body such as a planet.
• Mass is the amount of matter in something. Matter is anything that
has mass and takes up space.
Errors in Measurement
• A standard is a benchmark used to compare other measures.
Calibration is the process of determining how close a measured result
is to the true value.
• Accuracy is
how close
your
measurement
is to the
actual value.
• Precision is
how close a
group of
measurement
s are to each
other.
• Accuracy is how close your measurement is to the actual value.
• Precision is how close a group of measurements are to each other.
• Significant digits describe how
precise a number is. There are
several rules to follow when
counting significant digits.
• Class rule- only use 2 decimal
points (unless otherwise
instructed)
Which ruler will result in greater precision
if used to take repeated measurements? Why?