Flashcards on SI Units and Scientific Calculations
SI Units and Scientific Calculations: A Complete Guide
Tap to flip · Swipe to navigate
SI units and unit conversion
12 cards
Card 1
Question: Why do scientists use S.I. units instead of everyday units like bath tubs or egg-cups?
Answer: So everyone uses the same standard units and data can be compared reliably — S.I. units are universal for scientists.
Card 2
Question: What are the S.I. base units for mass, length, time, amount of substance and temperature?
Answer: Mass: kilogram (kg); Length: metre (m); Time: second (s); Amount: mole (mol); Temperature: kelvin (K).
Card 3
Question: What is the purpose of prefixes (like kilo-, milli-, micro-) attached to S.I. units?
Answer: They make numbers more manageable by creating larger or smaller units relative to the base unit (e.g. kilometre = 1000 metres).
Card 4
Question: Give the meaning (as a power of ten or multiplier) of these common prefixes: kilo (k), centi (c), milli (m), micro (μ), nano (n), mega (M), giga (G),
Answer: kilo (k)=1000; centi (c)=0.01; milli (m)=0.001; micro (μ)=0.000001; nano (n)=10⁻9; mega (M)=1,000,000; giga (G)=10⁹; tera (T)=10¹².
Card 5
Question: When converting from a bigger unit to a smaller unit (e.g. m to cm), do you multiply or divide by the conversion factor?
Answer: Multiply by the conversion factor to go from a bigger unit to a smaller unit.
Card 6
Question: When converting from a smaller unit to a bigger unit (e.g. g to kg), do you multiply or divide by the conversion factor?
Answer: Divide by the conversion factor to go from a smaller unit to a bigger unit.
Card 7
Question: What is a conversion factor in unit conversion?
Answer: The number you multiply or divide by to get from the original unit to the new unit.
Card 8
Question: Why must you check units before substituting values into formulas?
Answer: Because formulas require values in specific units (e.g. distance in metres for speed); wrong units give wrong answers, so convert first if needed.
Card 9
Question: What helpful practice is suggested to ensure units are correct during calculations?
Answer: Write down the units on each line of your calculation to track and check they are correct.
Card 10
Question: If you measured a trolley's distance in centimetres but the speed formula needs metres, what should you do first?
Answer: Convert the distance from centimetres to metres before using the formula.