# Physics - Physical Properties of Matter / Measurements / Density

** remember to add in diagrams later

## physical properties of matter

def: qualities that can be detected using our five senses / a measuring device.

• flexibilit ability to bend w/o breaking
• hardness ability to withstand scratches (if an x is scratched by y, then y is harder than x)
• melting point temp @ which smth changes state fr solid to liq
• boiling point  temp @ which smth changes state fr liq to gas
• thermal conductivity measure of how quickly heat passes through smth
• electrical conductivity measure of how readily electricity passes through smth
• density  quan. of matter packed into a unit vol of the mtrl (if an obj is put in a liq and it sinks, its density is > the density of the liq)

things to consider when choosing a mtrl to make smth:

• what purpose does the obj serve?
• what physical properties does the obj need to have?
• does the mtrl cost too much?
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## units of measurement**

SI units:

• length m
• mass  kg
• temp  K (Kelvin)
• time s
• volume  m3 [cm3, l, ml]

Other units:

• density g/cm3 or kg/m3
• pressure  Pa (Pascal) or N/m2 or N/cm2 (depending on the qn)
• force    N
• area   m2 or cm2
• energy/work  J
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## density

def.: the quantity of matter in a material packed into a unit volume of the material

formula: density = mass / volume

mass

• amt of matter in an obj
• does not change no matter where you go
• measured in g or kg

volume

• amt of space an obj occupies
• for the same amt of space a gas occupies, the vol may be diff bec gases are compressible
• measured in l, ml, cm3 or m3

density question - z grams of x is mixed with w grams of y to obtain a mixture. the volume of this mixture is z cm3. find the density of the mixture.

ans: total mass / total volume = density of the mixture

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