II.3.1. Physical parameter
📚 Summary - Physical parameter
A physical phenomenon (physical process) occurs when at least one of the physical properties that characterize a body changes over time.
Remark:
Following a physical phenomenon, the body does not change its substance.
Example of physical phenomena:
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Water boiling (water changes its state of aggregation, from liquid to gaseous);
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Body movement (changing the position of one body relative to another);
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Ice melting (water changes from solid to liquid);
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Sweetening the water by mixing it with sugar (water changes its taste);
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Lighting the bulb (the filament heats up);
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Stretching a bow etc.
| The result of measuring a physical quantity is given in the following form: |
|---|
| PHYSICAL PARAMETER (SYMBOL) = NUMERICAL VALUE ∙ MEASUREMENT UNIT (SYMBOL) |
Any measurement has limited accuracy and therefore the notion of measurement error appears.
Sources of error can be:
- lack of accuracy of the measuring instrument;
- incorrect reading of the instrument indications;
- the lack of attention or skill of the person making the measurements;
- unfavorable environmental conditions (inadequate lighting, too hot or too cold, discomfort etc.).
If we perform length measurements with a ruler, the measurement accuracy cannot exceed the smallest gradation of the ruler - respectively 1 mm.
So the measurement error due to the instrument used is equal to the smallest division of the instrument.
The existence of measurement errors in the case of experimental determinations is normal and in order to obtain a result as close as possible to the true value of the measured quantity, the measurements are repeated several times.
Result of the determination = The average value ± The absolute average error
l = laverage ± Δlaverage
