Measurement Systems English System (USA) –based on feet, pounds, gallons –Complex Metric (SI) system (everyone else) –Simpler –Based on powers of 10
a decimal system of measurement based on 10 Prefixes of SI used in this class: Kilo= 1000 Deci= 1/10 or 0.1 Centi= 1/100 or.01 milli= 1/1000 or.001
Measurements Must have both a number and a unit: –Ex: 4m Size of object determines size of unit used
Length Distance between 2 points
1km = 1000m 1m = 100cm 1cm = 10mm
Mass Mass: amount of matter in an object –Measured with a balance –Units = g or kg
Volume Volume: Amount of space taken up by an object. Units = liters (L), milliliters (mL), cm 3
Measuring Volume 3 Methods : 1.Volume of Regular solids (cubes, rectangles). V = length x width x height Volume = 5 cm x 5 cm x 5 cm = 125 cm 3 5 cm
2.Volume of a liquid Pour and measure –Use graduated cylinders
Reading a Graduated cylinder Record value at bottom of meniscus In this case 52.8 ml
Measuring Volume 3. Irregular solid (rock) by water Displacement Volume of water displaced = volume of object
Volume by water displacement
Density
Density = Mass/Volume Units = g/ml or g/cm 3
M DV
Buoyancy Ability of a fluid to exert an upward force on an object placed in it
Density & Buoyancy If object is less dense than the fluid it’s in, it floats If object is more dense than the fluid it’s in, it sinks Density of water = 1.0 g/mL
Temperature Measured with a thermometer SI base unit is Kelvin
Kelvin vs. Celsius Scale Celsius Scale: Water freezes at 0° C Water boils at 100° C
Kelvin Scale 0 K is called absolute zero. At 0 K all particles stop moving. Kelvin/Celsius Conversion K = °C + 273
Graphing Data
Why use Graphs? provides easy method of organizing data (picture) 3types of graphs 1.Bar: used for comparing data 2.Circle: shows how parts relates to a whole 3.Line: shows changes that occur between related variables
Bar Graph
Circle Graphs Parts always add up to 100%
Line Graphs Most scientific graphs are line graphs Lines can be straight
Line graphs Lines can also be curved