Introduction
This section of the course is very similar to Physics 2.1 that we covered last year. It involves carrying out an investigation, collecting, processing and transforming data accurately, then deriving an equation for the non-linear relationship from the transformed graph, followed by an evaluation of your investigation.
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Quantifying Uncertainty |
Useful Resources |
The size of the uncertainty in a measurement can be estimated by;
1. Using the smallest graduation on the measuring scale 2. Using half the range of repeated measurements This will give you the Absolute Uncertainty (e.g. 57.3± 0.1kg). Sometimes (when multiplying and dividing) we convert the uncertainty to a percentage and call it Relative Uncertainty (e.g. 57.3kg ± 1.75%) There are YouTube videos that are helpful on this including; Percentage Uncertainties Uncertainties |
Rules for Calculations with Uncertainties
Adding or subtracting measurements -add the absolute uncertainties (or multiply by a whole number)
eg. 3.5±0.2m + 2.4±0.1m = 5.9±0.3m
3.5±0.2m - 2.4±0.1m = 1.1±0.3m
Multiplying or dividing by a whole number -multiply or divide the absolute uncertainty by the whole number
eg. 3.5±0.2m x 3 =10.5±0.6m
3.5±0.2m ÷ 2 = 1.8±0.1m
Multiplying or dividing -add the relative uncertainties
eg. 3.5m±5% x 2.4m±7% = 8.41.1m±12%
3.5m±5% ÷ 2.4m±7% = 1.47m±12%
Raising to a power -multiply the relative uncertainty by the power
eg. (3.5m±5%)^2 = 12.25±10%
√3.5m±5% = 1.87±2.5%
A useful YouTube video is Combining Uncertainties
eg. 3.5±0.2m + 2.4±0.1m = 5.9±0.3m
3.5±0.2m - 2.4±0.1m = 1.1±0.3m
Multiplying or dividing by a whole number -multiply or divide the absolute uncertainty by the whole number
eg. 3.5±0.2m x 3 =10.5±0.6m
3.5±0.2m ÷ 2 = 1.8±0.1m
Multiplying or dividing -add the relative uncertainties
eg. 3.5m±5% x 2.4m±7% = 8.41.1m±12%
3.5m±5% ÷ 2.4m±7% = 1.47m±12%
Raising to a power -multiply the relative uncertainty by the power
eg. (3.5m±5%)^2 = 12.25±10%
√3.5m±5% = 1.87±2.5%
A useful YouTube video is Combining Uncertainties