# Volume, Density. Mass

• April 9th 2008, 03:41 PM
soccerchic96
Volume, Density. Mass
A rock has a density of 17 gm/cc. If it is cut into 3 equal pieces, what will be the dencity of each peice?
• April 9th 2008, 03:47 PM
topher0805
Uhmm.....

Density is defined as Mass divided by Volume. It's a ratio. So, when the rock is cut into 3, does that ratio change for any of the three pieces?
• April 9th 2008, 04:09 PM
soccerchic96
Need equation
No, the ratio doesn't change, but I don't know how to express it in a formula.
• April 9th 2008, 04:15 PM
topher0805
Try this:

$D_1=17$

$D_1=\frac {M}{V}$

So when the rock is cut into three equal pieces, the mass and volume are also cut into three equal pieces:

$D_2=\frac {\frac {M}{3}}{\frac {V}{3}}$

Remember that to divide fractions you flip and multiply. So:

$D_2=\frac {M}{3}\cdot \frac {3}{V}$

$D_2=\frac {M}{V}$

Therefore:

$D_2=D_1$

$D_2=17$