I. Measurement

A. qualitative - uses descriptions and words

B. quantitative - uses numbers and measurements

C. precision - agreement between numerical values of a set of measurements that have been made the same way

D. accuracy - how close a measurement is to its accepted value

%error =/ Observed-accepted/ x 100%

                        accepted

II. Scientific Notation

A. converting a number into - all numbers expressed in scientific notation have one non-zero digit to the left of the decimal and the others to the right; then multiply by some factor of ten; for example:

0.00456 =4.56 x 10^-3

456000 = 4.56 x 10⁵

RULE: as you move the decimal right, the exponent moves down

as you move the decimal left the exponent moves up
 

B. using in calculations (calculator review);

rule of thumb: keep only two decimal places and get rid of the rest .
 

III. Significant figures (GT)

A. definition - only those digits which are believable based on the skill of the investigator and the limitations of the measuring device; for example: you can read a temperature of 24.5•C but not 24.467•C; so the last two digits don't mean anything

B. rules for determining significant digits

1. every nonzero digit in a measurement is significant (24.5m, 0.546 ml)

2. zeros between nonzero digits are significant (50.7 m, 4007 km)

3. zeroes in front are Not significant only placeholders (0.05 mm)

4. zeroes at the end are NOT significant unless followed by a decimal point or written in scientific notation (3.0 x 10 4 m has 2 SIG figs)( 30 m has 1 SIG fig)

C. calculations

1. addition subtraction - the final answer may contain only as many digits to the right of the decimal as the number with the least digits to the right in the calculation
 
 
 
 

12.52 m

349.0 m

8.24 m

396.76 m -­> must be 396.8 m (round up)

2. multiplication / division - the final answer may only contain as many Sig figs as the number with the least SIG figs in the calculation

7.55m x O.34m=2.567m²-->mustbe2.6m²

. . . . . .