Measurement, Precision & Accuracy Activity

Conceptual Physics Activity 00a: Measurement, Precision and Accuracy Experimentation almost always involves measurements of length, mass, time, or other quantities. In making such measurements, we try to obtain as much precision as possible with the instruments and techniques available to us. We always pay attention to significant figures so as not to overstate (or understate!) the precision. In this simple activity, we will practice making indirect measurements and using the rules of significant figures which you have learned previously. Materials plastic beral pipet

graduated cylinder(s)

digital scale(s)

ruler(s)

Tasks Develop a viable method which will most precisely allow you to make the following measurements:

1 2 3

Determine the mass of one drop of water dispensed from a plastic beral pipet. Determine the volume of one drop of water dispensed from a plastic beral pipet. Determine the thickness of a 10.0 cm x 10.0 cm sample of aluminum foil.

Analysis: For each task, do the following: a. Write a clear and concise description of the method you used to obtain the measurements. b. Create a data table showing all measurements. Make sure that each column or row heading includes the appropriate units in parentheses. All data should show the correct number of significant figures. c. Show any calculations you used to determine the final measurement. Pay attention to the rules of significant figures. Include appropriate labels. Critical Thinking: Two students make measurements of the mass of a single drop of water, the volume of a single drop of water, and the thickness of the same sample of aluminum foil. Their results are outlined in the table below: Student A

Student B

Mass of 1 Drop of Water (g)

0.045

Mass of 1 Drop of Water (g)

0.05

Volume of 1 Drop of Water (mL)

0.045

Volume of 1 Drop of Water (mL)

0.05

Thickness of sample of Aluminum Foil (cm)

0.015

Thickness of sample of Aluminum Foil (cm)

0.02

1. How can the two students obtain different thicknesses for aluminum foil if they measured the same sample? Explain.

2. Suggest differences in equipment, measurements and/or calculations which could account for the discrepancies in measurements between student A and student B.