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Why do some things
float…
… and other things sink?
NOT because it is lighter than the liquid…
Some things float…
Two men on a tree trunk… definitely not lighter than
water
NOT because it is heavier than the
liquid…
And, some things sink…
A small marble is not heavier
than a beaker of water but it will
still sink
The MASS AND the VOLUME!!
So, density depends on…
That’s why the wood (and men)
don’t sink!!
volume = the amount of space an object takes up
Some vocabulary background…Mass = the amount of stuff that an object has
That is why a heavy metal ship can float on water…
Density = ratio of mass to the volume.
even though the mass is big, the volume is big too!!
Ratio means that density depends on both the mass AND the volume.
But, how do you calculate the density???
Density =mass
volume
Sample problemWhat is the density of 50.0 g of a solid which occupies a volume of 6.4 mL?the mass =the volume=
50.0 g6.4 mL
Density = mass
volumeD = 50.0 g / 6.4 mL
D = 7.8 g / mL
the equation=>
the unknown=
density
