Graphics Reference
In-Depth Information
FIG 4.7
The number of supports and
the spread between those supports
determines the stability of the object.
The center of gravity of a figure at rest may be maintained if supported by
an adequate number of supports over a wide enough area. However, for the
figure to move, the center of gravity must be shifted to ensure that balance
is maintained. An animal supporting its mass on four legs does so by even
distribution of the weight across the area defined by the point at which the
four legs touch the ground. If one of the legs is then lifted, a shift of the center
of gravity is necessary if stability is to be maintained. Then for the mass of the
body to be supported by the triangular configuration of the supporting legs,
the center of gravity must be relocated over the center of this triangle.
The point at which contact is made with the ground is also important. A
gazelle has relatively small contact points with the ground, but because it
has
four
such contact points, it is able to maintain its balance well. Humans
are also able to balance well, but they manage this on two legs and can even
manage reasonably well on one leg due to their relatively large feet, which
spread the contact with the ground over a larger surface area.
So far we have looked at how agility, speed, maneuverability, and stability
offer benefits to various animals. There is a balance to be struck between
these factors, and as so often is the case, a compromise in the design of the
animal is the result. The results are completely based on the suitability of one
or another animal to the individual species. The design solution, and therefore
an animal's agility, speed, or stability, is determined by the niche it has found
in nature. Sloths do not need to move quickly, but sparrow hawks do. Snakes
do not need to have high levels of stamina, but wildebeests do. A giant
tortoise does not require great agility; a squirrel does.
