Physical Constraints of Very Large Humanoids I loved Godzilla movies when I was a kid (still do), but ever since Pacific Rim came out, I have been pondering just how implausible really large humanoids would be given the laws of physics.
For the sake of this question lets say we have the following:


*

*Humanoid figure, proportional to an average human male

*30 meters tall

*Movements have similar timing to average human male

*Everything takes place on Earth


How strong would its body have to be to withstand the force of simply moving around? Is there any physical material we know of that could accomplish this?
What would happen to the environment around such an entity exerting such forces? Would the ground simply give too much to make quick movements like running impossible?
I am very interested in the math behind all of this.
 A: This is the line I have been working on, but using Male African Elephants,
and Dinosaurs with " n " Elephant Volumes , where the surface gravity of the
Earth is inversely proportional to the cube root of the n E.V. ( Elephant Volumes ).
n is limited to less than or equal to 13.0 E.V.  The number has been getting smaller
over the last 252 million years, which mean that the maximum allowable size of
animals is gradually getting less and less as time passes.
There are still some conundrums.
Why does a Dinosaur of 8 Elephant Volumes in a surface gravity of 0.5 g ( now )
only have twice the surface area of the bottom of its four feet ?
The downward force is 8 x 0.5 = 4, but the force per unit area ( pressure )
is 4 / 2 = 2 times the unit force of an Elephant. So why did they not get stuck
in the Mud?
Any way, to answer your questions, Humans are no where near the maximum allowable
limits of animal sizes in the current surface gravity, but there are some limits.
Limits: The size of the Pump ( heart ) , and the hydraulic pressure required to
pump blood to the brain, without bursting blood vessels in the legs and feet.
Structural Limits: The Elephant is at the Maximum allowed ( 40 % muscle mass )
and ( 27 % bone mass ). The upper limit is 67 %. The other 33% is for all the 
other non structural stuff ( all the organs, fluids, brain, nerves, connective tissues
and lots of other stuff ).
There is a tendency to maximize size in some animals, but this comes with a price.
The price is it takes lots of food to keep big animals big.  If the food becomes scarce,
the biggest animals in a species die off, while some smaller individual animals
still survive.
When you look at the pictures of the skeletons of large extinct humans, look for
telltale signs.  The relative dimension will change, the leg bones will be abnormally
long and robust, and the ends of the leg bones will be larger in comparison to the
cross-section at the mid height of the leg bones. The spine and head will be more
robust, and the arm bones also longer and more robust.
If the picture looks too skinny, or slender, it is a fake.  The overall proportions
need to look more like long cow legs, or bison legs, with large joints, especially the
Knee joints, and hip joints.
If you double the Height of a Human to 12 feet, then it will weight more like
8 times the weight of a current big human ( 250 lbs to 300 lbs ) becomes
2000 lbs to 2400 lbs.  This is not impossible, but the structural requirements of the 
bones, muscles, ligaments, and tendons have to be reflected in an appropriately
robust skeleton that would support this kind of weight.
You might also find spinal problems ( curved spines ). Short life spans ?
Low Population numbers ?  This would be an interesting thing to study.
They may have been quite possible before we hunted out the largest food
source animals around 8,000 to 10,000 years ago, and the climate changed
dramatically.
Food for thought.
