Density

 

 

n     Density is a measure of how tightly packed molecules are

 

 

n     Mass divided by volume

n    Mass # always goes into the calculator first even if it’s smaller

n    EX: If mass is 5.0 g and volume is 20.0 cm³ then d = 0.25 g/cm³

 

 

 

3 Important Density Facts

 

1.  Density does not change if you cut an object into pieces

ⁿ            EX: If you have a block with a density of 0.25 g/cm³ and you cut the block in half, its density will still be 0.25 g/cm³

 

Same material, so it’s the same density!

 

 

2.  Density can help predict whether an object will float in a liquid. 

n          If the object has a lower density then it will float

n          EX: A block that has a density of 0.9 g/cm³ will float in water (d = 1.0 g/cm³)
but will not float in oil (d = 0.8 g/cm³).

 

 

 

 

 

3.   Density values can predict where an object can float in water.

n          Just view the density as the % underwater

n        Mentally multiply density by 100.

n          Anything over 100% then it is at the bottom

 

 

Density Triangle – For Calculations

To use the density triangle, cover up the variable you need to find.  See how the other two variables are arranged.  That will give you the formula.  If the two variables are side by side, multiple.  If one variables sits atop another, divide.  See the examples below.