25.44 cm24.23 cm26.55 cm25.31 cm

25.46 cm25.45 cm25.47 cm25.46 cm

15.23 cm32.16 cm55.23 cm10.25 cm

42.24 cm42.23 cm42.22 cm42.23 cm

If the real measurement is 25.46 cm

Precision

Acc

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y

LowLo

wHigh

Hig

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Classwork

Do p. 29 #43-46

How to read a scale 1) Identify the difference between numbered divisions and unnumbered subdivisions.

diffrence b/w numbered divisions

numbered divisions

unnumbered subdivisions

5.3 5.4 5.5

difference b/w unnumbered subdivisions

2) Determine to what decimal place the estimated number value could be. For example: if the numbered division difference is 0.1 of a unit and the unnumbered difference is 0.01 of a unit, the estimated value when you look at the scale would be 0.001 of a unit. (0.1 times the unnumbered difference)

Example: What is the values of i and ii on the following scale?

5.9 6.0 6.1

i ii

• Count the number of unnumbered subdivisions between the numbered divisions: = 10.

• Find the value of each unnumbered subdivision: = difference between the number divisions divided by the number of subdivisions: (0.1/10 = 0.01)

• i is around 5.92 and ii is around 6.06.• Estimate where i and ii are between their unnumbered

subdivisions by dividing the unnumbered subdivisions into 10.– Reading i = is between 5.924 and 5.926. Is about halfway

between these two subdivisions, so it is estimated that i is 5.925 +/- 0.001.

– Reading ii = is between 6.062 and 6.064. Is closer to 6.06 than 6.07, so I would estimate that ii was 6.063 +/- 0.001.

Experimental UncertaintyDefinition: The experimental uncertainty is the estimated amount by which a measurement might be in error.• The uncertainty goes between the number and the unit. • The uncertainty is the number that was estimated, not a certain

number.

Example: 55.25 ± 0.01 cm.- This means that the actual temperature is between 55.24 cm and 55.26 cm.- Certain digits are 55.2 and the uncertain digit is 0.05.

Note: If the uncertain digit is in the second decimal place, the uncertainty will be in the second decimal place.

-The uncertainty in a measurement is 0.1 times the unnumbered subdivisions.

Homework

p. 32 – 36#48, 49, 50, 51, 52,