Every measurement device has its limitations You can only estimate to between the lines, but not beyond. Eg: a bathroom scale doesn’t give your weight to the thousandth of a pound Eg: diagram in book, p 133 So we can only record measurements to the next level between the lines we can see, because we cannot visually estimate further.
A beaker is never an accurate measurement device. For accurate liquid measurement, use a… Graduated cylinder The liquid in a graduated cylinder may form a curve, called a … Meniscus When reading a graduated cylinder, always read the _______ of the meniscus bottom
Water freezes at 32 ˚F and boils at 212 ˚F Water freezes at 0˚C and boils at 100˚C As things cool down, particles slow down The Kelvin temperature scale is based on absolute zero – a theoretical temperature at which electrons stop moving around nuclei and matter stands still There is no such thing as a negative Kelvin Kelvin is not stated as “degrees Kelvin”, but simply as “Kelvin”
Each Kelvin unit is exactly equal to one Celsius degree. 0 Kelvin = -273˚C Therefore 0 ˚C = 273 K Add 273 degrees to Celsius to get Kelvin Try these: 244 Kelvin = _______ Celsius -29 Water boils at ________ Kelvin 373 Water freezes at ________ Kelvin 273
How “packed” something is. Loosely “packed” = low density Tightly packed = high density A derived unit. To calculate… Mass ÷ volume We love density D = m/v m = … vd v = … m/d
compares the density of something to the density of water at 4 ˚C (when water is the most dense) specific gravity of water at 4 ˚C is 1.0 so, if an object floats, its specific gravity is (less than or greater than) 1?... less than 1 if an object sinks, its specific gravity is > 1
hand-out