To find the net mass of something do you subtract the average mass of an empty can from the average mass of cans of regular soda. So I can calculate the density of cola.
net mass of cola divided by volume of cola.
What does net mass mean?
The gross mass of a soda is the mass of the soda + the mass of the can.
Net mass of the soda is mass (soda+can) - mass empty can = mass soda..