This year I have pointed to a free election is called Physics in Science Fiction . We have to publish entries (though I'm a little delayed with the publications, I hope to catch up) trying on the various issues discussed in class and / or who had do with physics in movies, stories, sci-fi series ....
The first topic we have discussed have been the giant creatures and although now I will summarize and comment over at the classroom, then put something homegrown. The first movie I've seen "The Food of the Gods" (1976), which is based on a novel by HG Wells. Do not want to spoil the plot in case anyone is curious, and plans to see, yet the story is set on an island and after eating a strange substance animal beings become giants. We see huge rats, worms, wasps ... they really could not exist because they have been enlarged proportionately.
order to explain the inability of these creatures, we must apply the Law of the Scale [body increases proportionally in all 3 dimensions (x, y, z)] and, therefore, its volume increases by scale factor squared and cubed volume:
mass of giant creature = (altura c.g/altura inicial) 3 por la masa inicial
El ejemplo de clase lo hicimos con King Kong:
- Gorila Inicial: altura: 2 m masa: 200kg
- Gorila Gigante: altura: 15m masa: ¿?
m' = (15/2) 3 .200 à ¡¡ 84 Tm!!
Nada más y nada menos que nuestro gorila gigante pesaría 84 Tm. ¿Creéis que podría con su propio peso? ¿ O incluso aunque pudiese, podría moverse de la forma he does?
For the weight they would support the bones of the creature is necessary to calculate the relative strength. Depending on the animal is larger or smaller. Suppose we had initially Gorilla can support 2 times its weight Ropi p, ie yourself and your other like him. As:
Force on = weight bearable / animal weight
Therefore, the gorilla would be able to withstand 400kg.
The larger the size of the creature, the lower the relative strength which means they can charge even less weight.
Applying the Law of the scale, the first gorilla can we add 1 meter, 2m, ... so on up to 4 meters, which would be the most that could grow to in order to sustain itself. Therefore, the giant gorilla box (15 feet) would be impossible to exist.
For this reason there have been both size creatures on Earth and those we know are in the water because they move better. In the earth's surface could hardly move. Can not compare the tons of a blue whale (largest mammal) with tons of elephant (largest land mammal), this is due to the medium in which they live.
If moving water is better thanks to Archimedes' Principle : that "everyone says or body immersed in a fluid experiences a vertical and upward thrust equal to the weight of fluid evacuated. "
Similarly, no large creatures that have existed would be proportional, but need stronger bones and wide, hence it can have huge paws. To change the relative strength, cited above, it is necessary to change other body proportions and therefore would not be a huge gorilla gorilla-shaped, or a giant rat with a rat. Just have some resemblance to the original animal.
PS: As already I'm late, I will add later the second part of the giant creatures.
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