Terminal VelocityInvestigating 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/DigitalLibraryResourceView.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 measurements 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?