Suppose I have a rod that is 1 meter long. Its density at 1 end is 1 kg/meter. It increases linearly, so that at the other end, its density is 3 kg/meter. What is the mass of the rod? Hint: If a rod has a constant density , with units mass/unit length, then its mass is p x length. We don't have constant density in this case, but if we imagine chopping up the rod into tiny sections, each with length Ace, then they have approximately constant density (the density changes very little over the small length). If we add up the masses of these small sections, we get an approximate value for the total mass. How can we make this approximation precise? Upload Choose a File