Chpt 3 : Review Flashcards
Measurement
is the act of comparing an unknown quantity to a standard unit of measurement
Dimension
In science is a property that can be measured.
Instruments
Is any artificial device made for the purpose of refining, extending, or substituting for the human senses when measuring.
Unit
Is the segment of a dimension assigned a value of 1 for measuring purposes.
Observational bias
Is a flawed perspective on data that results from a person’s desire to see a certain outcome or from one’s limitations.
Measured data has two parts:
a number that gives the size of the measurement and the dimensional unit.
Metric system of measures
In 1799 France established a decimal metric system of measures consisting of the meter (m) and the kilogram (kg).
Cubic decimeter
Is equal to 1/1000 of a cubic meter
Prefix
Each prefix indicates the factor necessary to produce the required unit
Conversions factor
Is any factor equal to 1 that consists of a ratio of two units.
Conversion check
If the new unit is larger than the original unit, then the new number will be smaller than the original number.
≅
“approximately equal to.”
The measurement error
is the mathematical difference between the measured value and the actual value.
Accuracy
Evaluates how close a measurement is to the actual value.
Precision
evaluates how exactly a measuremen t is made.
exactness of measured data
is determined by reading the major and minor divisions on the instrument scale.
Significant digits
in a measurement are all the digits known from the instru- ment scale plus one estimated digit.
The purpose of observing significant digits
is to establish the precision of the measurement, not improve its accuracy.
SD Rules 3–5
describes how to deal with zeros in a measurement.
SD Rule 2:
All nonzero digits in measured data are significant.
SD Rule 1:
Significant digits apply only to measured data.
SD Rule 3:
All zeros between nonzero digits are significant.
SD Rule 4:
Decimal points define significant zeros.
SD Rule 5:
Significant zeros in the one’s place are followed by a dec- imal point.
Weight
can indicate the amount of matter in an object, but it does not measure the amount of matter directly.
Mass
Is the measure of the amount of matter in an object.
spring scale
It balances the pull of the earth’s gravity on an object being weighed against the pull of a spring inside the instrument.
electronic scale
The scale converts the pull of gravity on the object into an electronic signal that is processed by a computer chip.
volume
The space enclosed or occupied by an object
volume
length × width × height V = lwh
cube
volume = (edge × edge × edge)
V = e3
Rectangle
volume = length × width × height
V = lwh
Density
is a property of matter that can be used to identify certain kinds of matter, especially pure sub- stances.
Si
Système International
Metric ladder
Killo Hecta Deka Meter Deci Centi Millie
