Topic 1: Measurement and uncertainties Flashcards
What are the 6 fundamental SI units? (Hint, they are for the following quantities:)
- mass
- distance
- time
- electrical current
- amount of substance
- temperature
- Kilogram (kg)
- Meter (m)
- Second (s)
- Ampere (A)
- Mole (mol)
- Kelvin (K)
Convert N to SI units.
kg m / s^2
Convert J to SI units.
kg m^2 / s^2
What is the speed of light?
3 * 10^8 m
What are the only 2 scenarios when figures aren’t significant?
- in a number with a decimal point, all leading zeros are insignificant e.g. 0.015 has 2 s.f.
- in a whole number, any trailing zeros are insignificant
e.g. 750 has 2 s.f. - however any zeros that are not leading after a decimal point are significant
e.g. 0.0100 has 3 s.f.
When multiplying or dividing numbers, how many significant figures should you use?
You should not exceed the least precise value of the calculation and any answer any answer should be consistent with the number of significant figures of the given data in the question.
In multiplication/division, give the answer to the lowest __________.
Significant figure (S.F.)
In addition/subtraction, give the answer to the lowest ___________.
Decimal place (D.P.)
What are estimations often rounded to?
The nearest order of magnitude (power of 10)
What are orders of magnitude?
Numbers given in powers of 10 that are used to compare the size of physical data.
What is the cause of a random error?
Fluctuations in measurements centred around the true value (spread).
What is the cause of a systematic error?
Fixed shifts in measurements away from the true value.
What is the cause of a systematic error?
Fixed shifts in measurements away from the true value.
Which error is caused by bias?
Systematic error
Which error can be reduced by averaging over repeated measurements?
Random error
Which errors are the following scenarios?
- Fluctuations in room temperature
- The noise in circuits
- Incorrect method of measurement
- Human error
- Equipment calibration error such as the zero offset error
- Random error
- Random error
- Systematic error
- Random error
- Systematic error
What does an absolute uncertainty look like?
±Δx
What does a fractional uncertainty look like?
±Δx / x
What does a percentage uncertainty look like?
±Δx / x * 100
What would the uncertainty be for the following:
- y = a + b
- y = a * b
- y = a / b
- y = a - c
- y = a^b
- Δy=Δa+Δb (sum of absolute uncertainties)
- Δy/y=Δa/a+Δb/b (sum of fractional uncertainties)
- Δy/y=Δa/a+Δb/b (sum of fractional uncertainties)
- Δy=Δa+Δb (sum of absolute uncertainties)
- Δy/y=|n|Δa/a (|n| times fractional uncertainty)
What do error bars on a graph indicate?
Uncertainties
ADD QUESTIONS ON UNCERTAINTIES IN GRAPHS
What is a scalar quantity?
What is a vector quantity?
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