MEASUREMENT LIMITATIONS MEASUREMENT LIMITATIONS 1 ACCURACY HOW CLOSE

MEASUREMENT LIMITATIONS

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)

1. 3. 2. 4.

SIGNIFICANT FIGURES (DIGITS) • INDICATES PRECISION OF AN INSTRUMENT • DEFINITION: ALL 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: 275. 68 g = 5 SIG FIGS • 2) ZEROES BETWEEN 2 NONZERO DIGITS ARE SIGNIFICANT – EX: 1205 m. L = 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) –EX: 104 000 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: 104 000 m = 5 SIG FIGS

ST 1 • 4) ALL ZEROES IN FRONT OF THE NON-ZERO DIGIT IN A NUMBER LESS THAN 1 ARE NOT SIGNIFICANT. (THEY ARE PLACEHOLDERS) –EX: 0. 00589 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: 0. 07050 L = 4 SIG FIGS 30. 00 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. – 1. 5600 m 2. 0. 0078 L – 3. 30024 g 4. 780. 0 ng – 5. 34. 078 m. L 6. 0. 002008 km – 7. 1000 PIES 8. 50. 091 d. L