Physics Unit 1 Measurement and Numbers Test Flashcards
Numbers as Measurements
A number is not a measurement (e.g. 5) It requires a unit so you know what you’re measuring.
SI
- Systeme International
- created in 1960 to standardize measurement and measurement devices
- 7 units - three of which we know:
- distance: meters (m)
- time: seconds (s)
Nano
10^-9, n
Micro
10^-6, µ
Milli
10^-3, m
Centi
10^-2, c
Deci
10^-1, d
Kilo
10^3, k
Mega
10^6, M
Giga
10^9, G
Sig Fig Counting Rules
- 1-9 rule: all digits 1-9 are significant figures
- Sandwich rule: all zeros that fall between two sig figs are also significant
- Decimal rule: zeros that fall to the right of the decimal and after a sig fig are significant
- Trailing rule: zeros that trail before a decimal are not necessarily significant
Sig Fig Calculating Rules: ÷x
The Least Rule: the number with the least number of sig figs in a problem dictates the number of sig figs in the answer
Sig Fig Calculating Rules: +-
The Line Rule: the least amount of places to the right of the decimal dictates the amount of decimal places in the answer
How many types of error are there?
4
Human error
a mistake one makes reading or recording results
Instrument error
your measuring device isn’t working properly
Parallax error
over or under-estimating a measurement because your eye line is not directly in front/on top of the measurement you’re reading
Method error
taking measurements in two different ways
Accuracy
your ability to measure against a known true value (e.g. your ability to hit a bullseye in archery)
Precision
your ability to reproduce a measurement (e.g. your ability to hit the bullseye three times in a row)
