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?
Try this:
$\displaystyle D_1=17$
$\displaystyle D_1=\frac {M}{V}$
So when the rock is cut into three equal pieces, the mass and volume are also cut into three equal pieces:
$\displaystyle D_2=\frac {\frac {M}{3}}{\frac {V}{3}}$
Remember that to divide fractions you flip and multiply. So:
$\displaystyle D_2=\frac {M}{3}\cdot \frac {3}{V}$
$\displaystyle D_2=\frac {M}{V}$
Therefore:
$\displaystyle D_2=D_1$
$\displaystyle D_2=17$