MEASUREMENT LIMITATIONS

1) ACCURACY – HOW CLOSE THE MEASUREMENT IS TO AN ACTUAL OR ACCEPTED VALUE – DEPENDS ON YOU – GETS BETTER WITH PRACTICE

% ERROR ALLOWS YOU TO EVALUATE THE ACCURACY OF YOUR DATA EQUATION:

2) PRECISION – AGREEMENT OF A SET OF VALUES – REPRODUCIBILITY OF DATA – MEASUREMENTS CAN ONLY BE AS PRECISE AS YOUR MEASURING TOOL (BASED ON HOW GRADUATED IT IS)

SIGNIFICANT FIGURES (DIGITS) INDICATES PRECISION OF AN INSTRUMENT DEFINITION: A LL CERTAIN VALUES (FROM GRADUATIONS ON TOOL) AND ONE ESTIMATED OR UNCERTAIN VALUE (SPACE BETWEEN LAST GRADUATIONS)

READING A METER STICK FOR PRECISION SEE SIDE BOARD. COPY DOWN INFORMATION AS TEACHER EXPLAINS.

RULES OF SIGNIFICANT DIGITS 1)ALL NONZERO DIGITS ARE SIGNIFICANT – EX: g = 5 SIG FIGS 2) ZEROES BETWEEN 2 NONZERO DIGITS ARE SIGNIFICANT – EX: 1205 mL = 4 SIG FIGS

3) ALL ZEROES AFTER THE LAST NON-ZERO DIGIT IN A NUMBER WITH AN UNDERSTOOD DECIMAL ARE NOT SIGNIFICANT. (THEY ARE PLACEHOLDERS) –E–EX: m = 3 SIG FIGS *THE NUMBER HAS BEEN ROUNDED

IF YOU WANT TO MAKE ZEROES SIGNIFICANT IN A NUMBER WITH AN UNDERSTOOD DECIMAL, PLACE A LINE OVER THE LAST ZERO THAT IS SIGNIFICANT. – EX: m = 5 SIG FIGS

4) ALL ZEROES IN FRONT OF THE 1 ST NON-ZERO DIGIT IN A NUMBER LESS THAN 1 ARE NOT SIGNIFICANT. (THEY ARE PLACEHOLDERS) –E–EX: g = 3 SIG. FIGS *THINK OF THESE NUMBERS AS FRACTIONS; ONLY SIG FIGS GO IN THE NUMERATOR

5) ALL ZEROES AFTER A DECIMAL AND AFTER THE 1 ST NON-ZERO DIGIT ARE SIGNIFICANT – EX: L = 4 SIG FIGS mg = 4 SIG FIGS *BE CAREFUL BECAUSE YOUR CALCULATOR REMOVES THE ZEROES AT THE END OF NUMBERS

6) ITEM COUNTS HAVE UNLIMITED SIG. FIGS. – EX: 10 APPLES → UNLIMITED 60 s = 1 min → UNLIMITED

PRACTICE PROBLEMS COPY AND ANSWER IN YOUR NOTEBOOK. PUT A BOX AROUND THE SIG FIGS. – m L – g ng – mL km – PIES dL