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Numbers and Measurements Measurement – the determination of a physical property of the sample of interest Dimension (length, width, height) Mass Capacity.

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Presentation on theme: "Numbers and Measurements Measurement – the determination of a physical property of the sample of interest Dimension (length, width, height) Mass Capacity."— Presentation transcript:

1 Numbers and Measurements Measurement – the determination of a physical property of the sample of interest Dimension (length, width, height) Mass Capacity (how many marbles will fit in this box?) Quantity Accuracy How close a measurement comes to the true value Precision How close a series of measurements are to each other

2 Numbers and Measurements Good Accuracy Good Precision Accuracy How close a measurement comes to the true value Precision How close a series of measurements are to each other Poor Accuracy Good Precision Poor Accuracy Poor Precision

3 Numbers and Units Measurements always contain: Number, Uncertainty and a UNIT Measurable value Standard against which the quantity is compared. Error in measured value Internationally accepted system of measurements is called the Systéme Internationale dUnités (SI)

4 Error in Measurements All measurements have uncertainty Thermometer A 45 ± 2 ˚C Thermometer B 44.7 ± 0.1

5 Significant Figures Numbers in any measurement that are known with certainty with one more number that is uncertain Thermometer A 45 ± 2 ˚C Thermometer B 44.7 ± significant figures 3 significant figures

6 Significant Figures Rule 1 Non-zeroes are ALWAYS significant Rule 2 Leading zeroes are NEVER significant Rule 3 Confined zeroes are ALWAYS significant Rule 4 Trailing zeroes are significant IF they accompany decimal point


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