Standards of Measurement
Units and Standards A standard is an exact quantity that people agree to use for comparison If different measurements are made using the same standard we can compare them
Le Systeme Internationale d’Unites The International System of Units was developed in 1960 We now call this the SI system for short SI is a set of standards that are universally accepted and used by scientists around the world
Measurement Systems What is the purpose of a standard?
Measurement Systems The SI system is based on multiples of 10 Prefixes are used to show which multiple of 10 is being used Prefix Symbol Multiplying Factor Kilo- k 1,000 Deci- d 0.1 Centi- c 0.01 Milli- m 0.001 Micro- µ 0.000 001 Nano- n 0.000 000 001
What will we be measuring? Length Volume Density Time Temperature
Length We use length to measure size and distance Meter, centimeter, kilometer
Volume Volume is the amount of space occupied by an object 1ml = 1cm3 Liters, milliliters
Matter Matter is anything that takes up space Mass is a measurement of the quantity of matter in an object Grams, kilograms
Density Density is the mass per unit of volume of an object g/cm3 How much matter is in a given space g/cm3
Time The SI unit for time is the Second (s) 60 s = 1 min 3,600 s = 60 min = 1 hr
Temperature The SI unit for temperature is the kelvin (K) Zero on the kelvin scale (0 K) is the coldest possible temperature – absolute zero 0 K = -273 ºC 273 ºC below the freezing point of water!!! COLD!
Freezing point of Water Temperature The kelvin scale is based on absolute zero (-273 ºC) Kelvin Celsius Fahrenheit Freezing point of Water 273 K 0 ºC 32 ºF Boiling point of Water 373 K 100 ºC 212 ºF
Converting SI units How do we convert between units? You have a length of rope that measures 3,075mm. How long is it in centimeters? Your drive to school is 12.4km. How far is it in meters?
(Write neatly!! This one can be tricky if you lose your place!) Converting SI units The speed limit on the Northway is 65mph. Convert 65mph to km/h. 1 mile = 1.61km Once you have calculated km/h, convert your answer to m/s. (Write neatly!! This one can be tricky if you lose your place!)