Anyhow, to answer your original question:
Originally Posted by rockouthippie
I figured out a while ago that I couldn't take 2 16 oz cans of pop and hang it off the handle bars on my bike. The bag would rip and fall on the ground. I have to double bag it. It's not even close. Obviously would rip out.
But I can put 4 cans in a double bag, and it doesn't rip. No evidence that it would rip at all.
...I assume that is has to do with how the force is distributed around the bag(s). Pressure is the force per unit area applied in a direction perpendicular to the surface of an object, i.e. force/area, force itself being a product of mass and acceleration due to gravity. It's not going to be a linear relationship because doubling the number of cans in the bag (mass) doesn't double the pressure on the bag's surface - it spreads the force over a larger area. Therefore four cans in two bags will apply less pressure than two cans in one bag.
Additionally, with four cans, the bags are kept in tension, and can't bounce around. Two cans can bounce around (increase in acceleration and therefore force, and therefore pressure). So again, more pressure in the single bag with two cans, than in the double bags with four cans.