Science - measurement

• a quantity is an exact amount or number of " things "
• a physical quantity is a quantity that can be measured.
• The SI UNITS are based on the metric system ( numbers ) e.g. cm
• The SI UNITS are the international system used to measure physical quantities.
• William Thompson , 1st Barron Kelvin was a mathematical physicist And engineer from Belfast.
• Absolute temperatures are named after William Thompson for his work.
• Absolutely zero is OK or -273.15°c
• The Kevin is the SI UNIT for temperature.
• We collect data on physical quantities to be able to: gather evidence to be able to test a hypothesis, have numerical evidence to explain why something works the way it does, to see the relationship between quantities being measured.
• The SI unit for length is a metre. (m)
• Other units such as millimetres, centimetres and kilometres are also part of the SI system
• Derived units are a combination of the the fundamental SI UNITS in different ways
• Some derived si units are: area, volume, density, speed and acceleration. ( They all involve distance / length. )
• These physical quantities ALL involve distance/length in their measurement.
• Area is a very useful physical quantity derived From Length
• Area is the amount of space a 2-D shape takes up.
• The si unit For area is m² ( m x m )
• To measure area multiply length by width.
• Mass = amount of matter in an object
• SI Unit for volume is m³
• SI Unit for mass is kg
• Volume can be measured using a measuring cylinder or graduated cylinder.
• Volume is how much space an object takes up.
• The SI unit for volume is cubic metres (m3).
• Temperature is a SI unit that can measure how hot or cold something is.
• We use a therometer to measure temperature
• We can measure time using a clock , stopwatch , hourglass etc. There are variety of tools.
• Density is how much matter something has compared to the amount of space it takes up. In scientific terms this is the ratio of mass to volume -> DENSITY is mass ( kg ) over volume ( m3 )
• The SI unit of density is kg / m3
• To calculate density , you divide the mass of the object by its volume.. when you get the answer it should be written as (answer grams ) per cm3
• The Instruments you would use to measure length are : Ruler , Metre stick , Opisometre, Trundle wheel, Micro metre and Vernier calliper
• The ratio of density is mass to volume.
• The meniscus is the curved surface of a liquid
• To take accurate measurements we read at eye level from the bottom of the meniscus