1. By Dr. Hong Zhang For Freshman Engineering Clinic

2.  Also called Significant digit  Any digit used in writing a number, except those zeros that are used only for location of the decimal point or those zeros that do not have any nonzero digit on their left.

3.  0.01234 kg  0.012340 kg  0.000011010 m  0.3100 m  321,010,000 miles  84,000 mg  32.00 mL  302.120 lbs 1.234 x 10-2 kg 1.2340 x 10-2 kg 1.1010 x 10-5 m 3.100 x 10-1 m 3.2101 x 106 miles 8.4 x 104 mg 3.200 x 101 mL 3.02120 x 102 lbs 4554524645545246

4.  Exact numbers are known with complete certainty.  They can be considered to have an infinite number of significant figures.  Many exact numbers are integers. For example, 1 ft = 12 inches. 12 is an exact number.

5. _ The number of students in this classroom _ The number of ounces in one pound _ The number of population in the state _ The number of inches per meter _ The number of garbage generated by a person _ The speed of light in vacuum _ The speed of a light truck

6.  If the diameter of the circle is 23.4 cm, what is the total area? π*(23.4/2) 2 =430cm 2 =4.30*10 -2 cm 2

7. Measure is to read between the scale division marks. That is, to estimate the measurement to the nearest one tenth of the space between scale divisions

8. What is the length of the beetle‘s body? _ Between 0 and 2 in _ Between 1 and 2 in _ Between 1.5 and 1.6 in _ Between 1.55 and 1.56 in _ Between 1.556 and 1.557 in

9. What is the length of the beetle‘s body? Between 1.55 and 1.56 in Any measurement made by comparing an object to a scale should include not only the certain digits (1.5 in this case) but also one estimated (uncertain) digit.

10. What is the penny‘s diameter? _ Between 0 and 2 cm _ Between 1 and 2 cm _ Between 1.9 and 2.0 cm _ Between 1.92 and 1.94 cm _ Between 1.935 and 1.945 cm

11. Left: Right: 1.4 in 1.48 in

12. Left: Mid ： Right: 5.72 ml 3.0 ml 0.35ml

13. 73°F or 23°C30.0°C

15. Use a physical measurement calibrated to some other physical scale A spring deflects linearly with an applied force

16. Convert one form of energy into another (usually a voltage or current) Force transducers (load cell) use a strain gauge which is attached to a piece of metal that flexes slightly from an applied force The strain gauge changes resistance when flexed This can be measured in the form of a voltage

17. Convert voltages and currents into a digital signal which is processed and used as information for display, sensors, etc..

18.  Calibrate measuring equipment  Organization is essential before and after an experiment  Consistency in measurement necessary  Record notes of test conditions

19.  Accuracy is a measure of the nearness of a value to the correct or true value.  Precision refers to the repeatability of a measurement, or how close successive measurements are to each other.

21.  The range of a permissible error can also be expressed as a percentage of the value. Consider a thermometer where the accuracy is given as + 1% of full scale. If the full scale reading is 220 o F then readings should be within + 2.2 o of the true value, i.e., 220x0.01=2.2

22.  Occurs from a device being not calibrated properly  An offset can be applied to measured value to correct it

23.  Show up as scatter in collected data  Comes from a variety of sources ◦ Human error ◦ Electrical noise ◦ Etc.