Alison Blanchard, of Rangi Ruru Girls School, asks :-

Which is stronger weight for weight, an ant or a human being?

Reg Dunlop, a University of Canterbury mechanical engineer who specialised in robotics, responded.

The ant is stronger. I don't know much about ants but I'd love to be able to make a "roboant" with the same size and strength as an ant.

While a human can pick up and carry a heavier weight for a greater distance than an ant, the ant can carry much more in terms of its body weight, and for longer distances in terms of its body length.

Often small sized creatures are stronger in terms of being able to carry items that weigh more than they do. The load carrying capacity of bones depends on the area through the bone (or external skeleton). Thus if the creature is made twice as big, the length of the bone is also doubled (x2), but the area becomes four times larger and the bone can carry four times (2x2) as much weight. The body weight depends on the volume of the creature, so if the size is doubled, the weight increases by eight times (2x2x2).

Thus if an ant was made twice as big, its "bones" would need to be eight times larger in cross-sectional area i.e. almost three times thicker for it to be as strong as before. If scaled up to human size, most of an ant's strength would be used up just carrying around the bigger body, and the strength would be similar to that of a human.

Here is something for you to think about. Why do moa and dinosaur have such large heavy bones.