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Measuring. Accuracy v. Precision pg. 8. Precision - how closely the measurements match each other. Instruments that measure using more decimals are more precise. Accuracy – how closely the measurement matches the true or accepted value. Accurate. Precise. Accurate. Precise. Accurate.
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Accuracy v. Precision pg. 8 Precision - how closely the measurements match each other. Instruments that measure using more decimals are more precise. Accuracy – how closely the measurement matches the true or accepted value.
Accurate Precise
Accurate • Precise
Accurate • Precise
Accurate • Precise
Accurate • Precise
How To Read Scientific Instruments • 1) Record the _______ digit on the instrument. • 2) Then _______________ the last digit.
How to Count Significant Figures Count all of the digits you are sure of. Add the last digit you estimate.
Percent Error • When quantities have accepted or true values, we can calculate the percent error between our measurement of the value and the accepted value with the formula
How to Read a Graduated Cylinder • Sit the graduated cylinder on a level surface. • Lower your eyes to the level of the liquid (called the meniscus). • Take your reading from the bottom of the meniscus. • Count all of the digits you are sure of. • Add the last digit that you estimate.
Quiz • Number your paper 1 to 15.
1) Measuring Length 2 cm 19 cm 1.95 cm 1.95238 cm
2) Measuring Length • 10cm • 1.1cm • 1.05cm • 1.526cm
3) Measuring Length • 17 cm • 17.5 cm • 18.0 cm • 17.5082 cm
4) Measuring Length • 4cm • 4.3cm • 4.30cm • 4.3057cm
5) Measuring Length • 12 cm • 12.0 cm • 12.7 cm • 12.0953 cm
6) Measuring Liquids • The meniscus is the curve in the upper surface of a liquid close to the surface of the container or another object, caused by surface tension. It can be either convex or concave. Is this meniscus convex or concave? 6) _________________ For questions 7 to 12, measure the amount of liquid in each graduated cylinder by reading the bottom of the meniscus.
7) Measuring Liquid Volume • 10ml • 10.3ml • 11.5ml • 13.0ml
8) Measuring Liquid Volume • 266 ml • 287 ml • 290 ml • 294 ml
9) Measuring Liquid Volume • 52 ml • 53 ml • 54.5 ml • 52.8 ml
10) Measuring Liquid Volume • 80 ml • 80.0 ml • 81.0 ml • 79.0 ml
11) Measuring Liquid Volume • 2.8 ml • 2.80 ml • 2.90 ml • 2.9 ml
12) Measuring Liquid Volume • 4.90 ml • 4.80 ml • 5.0 ml • 5.0853 ml
13) Measuring Solids • 625.62g • 26.57g • 265.73 • 526.6g
14) Measuring Solids • 373.33g • 734.33g • 374.33g • 373.3g
15) Measuring Solids • 222.50g • 221.50g • 221.5g • 221.0g