1. Measurements and uncertainties

1.1 – Measurements in physics

Nature of science:

Common terminology: Since the 18th century, scientists have sought to establish common systems of measurements to facilitate international collaboration across science disciplines and ensure replication and comparability of experimental findings. Improvement in instrumentation: An improvement in apparatus and instrumentation, such as using the transition of cesium-133 atoms for atomic clocks, has led to more refined definitions of standard units. Certainty: Although scientists are perceived as working towards finding “exact” answers, the unavoidable uncertainty in any measurement always exists.

Understandings:

Applications and skills:

Using SI units in the correct format for all required measurements, final answers to calculations and presentation of raw and processed data
Using scientific notation and metric multipliers
Quoting and comparing ratios, values and approximations to the nearest order of magnitude
Estimating quantities to an appropriate number of significant figures

Nature of science:

Uncertainties: “All scientific knowledge is uncertain… if you have made up your mind already, you might not solve it. When the scientist tells you he does not know the answer, he is an ignorant man. When he tells you he has a hunch about how it is going to work, he is uncertain about it. When he is pretty sure of how it is going to work, and he tells you, ‘This is the way it’s going to work, I’ll bet,’ he still is in some doubt. And it is of paramount importance, in order to make progress, that we recognize this ignorance and this doubt. Because we have the doubt, we then propose looking in new directions for new ideas.” Feynman, Richard P. 1998. The Meaning of It All: Thoughts of a Citizen-Scientist. Reading, Massachusetts, USA. Perseus. P 13.

Understandings:

Applications and skills:

Explaining how random and systematic errors can be identified and reduced
Collecting data that include absolute and/or fractional uncertainties and stating these as an uncertainty range (expressed as: best estimate ± uncertainty range)
Propagating uncertainties through calculations involving addition, subtraction, multiplication, division and raising to a power
Determining the uncertainty in gradients and intercepts

Nature of science:

Models: First mentioned explicitly in a scientific paper in 1846, scalars and vectors reflected the work of scientists and mathematicians across the globe for over 300 years on representing measurements in three-dimensional space.

Understandings:

Applications and skills:

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