Chapter 2 Numbers from Measurments Flashcards
Measurement
The determination of the dimensions, capacity, quantity, or extent of something.
Mass, volume, length, time, etc.
Exact Number
number that has no uncertainty in it
Inexact Number
number that carries a degree of uncertainty. Every measurement has uncertainty to it.
Precision
How close a series of measurements are two each other.
Accuracy
How close to the true measurement a measurement( or series of measurements) is.
Random Error
Error typically generated by some fluctuation in something uncontrollable.
Systematic Error
Error originating from controllable variables in an experiment. They are constant. Something such as a flawed piece of equipment
Uncertainty
When a measurement is made only one digit is recorded to represent uncertainty. i.e. 15 is uncertain in the ones place, 15.3 is uncertain in the tenths place.
Significant Figures
digits in any measurement that are known with certainty plus one digit that is uncertain
Human Error
Errors resulting from human limits such as how well a measurement is read or how well a machine is calibrated
Instrument Error
Errors originating specifically from the instruments flaws.
Rules for Significant Figures
1) All nonzero digits are significant
2) All leading zeroes are insignificant
3) Confine zeroes are always significant
4) Trailing zeroes are only significant if there is a decimal point present
Rounding Off
the process of deleting unwanted (non significant) digits from a calculator number
Rules for Rounding Off
1) If the first digit to be dropped is less than five then the first sig fig is left the same
2) If the first digit to be dropped is 5 or greater with a nonzero digit after it then the first sig fig is increased by one
3) If the first digit dropped is exactly 5 followed by zeroes or no digits then if the first sig fig is odd raise it. If it’s even leave it be
Sig Fig Rule for Multiplication/ Division
the number of sig figs in the product or quotient is the same as the number in the calculation that contains the fewest sig figs.
Sig Fig Rules for Addition/ Subtraction
the uncertainty in the answer should be the same as that of the measurement that has the greatest uncertainty. Also remember if a decimal point is present(34.000 = 5 sig figs) than uncertainty is to where the last zero is
Order of Magnitude
a signal exponential value of the number 10.
i.e. 10^6 is four orders of magnitude larger than 10^2
Multiplication in Scientific Notation
1) multiply coefficients together
2) add the exponents together to get a new power of 10
Division in Scientific Notation
1) divide coefficients
2) subtract exponents to get a new power of ten
3) calculator answer must be fixed for sig figs
Addition/ Subtraction in Scientific Notation
1) all powers of ten must be the same
2) when exponents are the same coefficients are added/subtracted
3) calculator answer must be fixed for sig figs
