ured length.  Measurement errors are another type of uncertainty involved in single measurements. Suppose we measure the diameter of a disk. The minimum length that can be measured on the stick is 1 mm (0.1 cm). If the diameter lies somewhere between 5.1 cm and 5.2 cm, which value do we report? In such cases the value is reported as 5.15 ± 0.05 cm. Note that the uncertainty of the measurement is one half the smallest tick mark on the measuring device. This applies to all instruments. A sound experimental procedure involves several measurements of the physical quantities required in one of several ways. Once those measurements have been made, we compute the statistical quantities listed in the key concepts above to make inferences from the data obtained. Question 1 (write down answers on Report Sheets) Below are three sets of measurements of the boiling point of water at 1 standard atmosphere (atm): Measurement 1 2 3 4 5 Set A 99.8 °C 99.8 °C 99.8 °C 99.8 °C 99.8 °C Set B 100.0

  T = (99.78 ±0.05) ºC

Explanation:

This problem refers to the procedure to perform the measurements and their correct reporting.

Suppose that the thermometer used has an appreciation of 0.1ºC and the values of 5 measurements resulted in

 #     T (ºC)

 1      99.8

 2     99.7

 3     99.7

 4     99.8

 5     99.9

the processing calculate mean value

   T_average = ∑ / n

   T_average = (99.8 + 99.7 + 99.7 + 99.8 + 99.9) / 5

   T_average = 99.78ºC

the absolute error or uncertainty of the measurement is half the appreciation of the instrument

       ΔT = ± 0.05ºC

so the result must be written

        T = (99.78 ±0.05) ºC

wire in brush may conduct electricity from cell to drill and vice versa electrc shock possible

a.metals can become magnetic if they have many spinning electrons that create magnetic fields.d.only some metals are attracted by magnets; these metals are called ferromagnetic.

d.wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current.