hl physics 2nd edition.pdf
Measurements in physics
If used properly a Vernier
calliper can measure small
lengths to within ±0.02 mm.
Since 1948, the Système International d’Unités (SI) has been used
as the preferred language of science and technology across the
globe and reflects current best measurement practice. A common
standard approach is necessary so units ‘are readily available to all,
are constant through time and space, and are easy to realize with
high accuracy’ – France: Bureau International des Poids et Mesures,
organisation intergouvernementale de la Convention du Mètre, The
International System of Units (SI), Bureau International des Poids et
Mesures, March 2006. Web: 21 May 2012.
Uncertainties and errors
Scientists aim towards designing experiments that can give a ‘true value’
from their measurements, but due to the limited precision in measuring
devices they often quote their results with some form of uncertainty.
Vectors and scalars
Some quantities have direction and magnitude, others have
magnitude only, and this understanding is key to correct
manipulation of quantities. This subtopic will have broad applications
across multiple fields within physics and other sciences.
NATURE OF SCIENCE
Physics is about modelling the physical Universe so that we can predict outcomes but
before we can develop models we need to define quantities and measure them. To
measure a quantity we first need to invent a measuring device and define a unit. When
measuring we should try to be as accurate as possible but we can never be exact,
measurements will always have uncertainties. This could be due to the instrument or
the way we use it or it might be that the quantity we are trying to measure is changing.
Measurements in physics
1.1 Measurements in physics
Understandings, applications, and skills:
Fundamental and derived SI units
Using SI units in the correct format for all required measurements, final answers to calculations
and presentation of raw and processed data.
SI unit usage and information can be found at the website of Bureau International des Poids et
Mesures. Students will not need to know the definition of SI units except where explicitly stated in the
relevant topics. Candela is not a required SI unit for this course.
Scientific notation and metric multipliers
● Using scientific notation and metric multipliers.
Orders of magnitude
● Quoting and comparing ratios, values, and approximations to the nearest order of magnitude.
● Estimating quantities to an appropriate number of significant figures.