Units of Measurement Flashcards
How many base units are there in the International System of Units?
There are 7 base units m (meter) length kg (kilogram) mass s (second) time A (ampere) electric current K (kelvin) temperature cd (candela) luminous intensity mol (mole) amount of substance
How is a kilogram kept universal?
The kilogram is kept universal as it refers to the weight of a chunk of platinum and iridium known as the international prototype kilogram or IPK
How is speed measured?
Speed = m/s = length/time
How is Acceleration measured?
Acceleration = m/s2 = length/time per second per second
How is Force measured?
Force = Newton = N = kg:m2/s2 = Acceleration x Mass
How is Work measured?
Joule = J = kg:m2/s2 = Force x Distance
How is Power measured?
Power = Watt = W = J/s = kg:m2/s3 = Work/Time
Who said “True greatness is when your name - like Hertz or Watt - is spelled with a lower case letter”?
Richard Hamming
What does a second represent?
A second is one sixtieth of one sixtieth of one twenty fourth of a single complete rotation of the earth. (earth’s rotation is gradually slowing down so leap seconds are added every few years to balance to difference)
What is a measured number?
A measured number is a number that represents a measurement taken. It shows the number that was measured and the precision at which the measurement was taken.
What is a Significant Figure?
Significant Figures (Sig Figs) are numbers in the calculation we actually know. For example to what decimal place we KNOW the value.
What is 0 sometimes used as?
A place holder.
What is scientific notation?
Scientific notation is used to write large numbers with less digits. For example:
60 = 6.0 x 10^1
The exponent tells us how far to move the decimal place
Why is it important to preserve sig figs in calculations?
Sig figs are the numbers we know the value of. If they aren’t preserved the calculations will contain values to which we don’t know the true value of.
Always Preserve Sig Figs
2.5490 x 10^-4 = 0.00024590
How many decimal places should your answer of your calculations have?
Ensure your answers to calculations always have the same amount of decimal places as the sig fig with the least amount of decimal places. This allows you to answer as truthfully and precisely as your most least precise measurement.
