I don't know who De Vaca is but by context clues I would infer that he realized that Native Americans where not the savages they where thought to be.
Answer:
In the science of conservation of energy, the law of conservation of energy is accounted for ruling and leading position. Other laws will be derived by the law of conservation of energy, or verified by the law of conservation of energy. In this paper four questions are discussed. The relationship between force and mass, velocity is reconsidered according to the law of conservation of energy; Other laws such as the law of gravity and law of Coulomb are re-derived; Other laws will be verified that whether or not they can be used, and an example that the law of conservation of momentum and the law of conservation of angular momentum are not correct (the results given by them are contradiction with the law of conservation of energy); Changing an old subject into a new subject. For example, changing Newton's mechanics into New Newton's mechanics ; New Newton's mechanics can be used for partly replacing relativity and solving the problem which can not be solved by relativity.
Citations: MLA
Yuhua, Fu. "Science of conservation of energy." Journal of Dezhou University 6 (2004): 20-24.
APA
Yuhua, F. (2004). Science of conservation of energy. Journal of Dezhou University, 6, 20-24.
Chicago
Yuhua, Fu. "Science of conservation of energy." Journal of Dezhou University 6 (2004): 20-24.
Harvard
Yuhua, F., 2004. Science of conservation of energy. Journal of Dezhou University, 6, pp.20-24.
Vancouver
Yuhua F. Science of conservation of energy. Journal of Dezhou University. 2004;6:20-4.
It was there own way of communicating which can improve various things.
Crossing the Rio Grande, thereby getting wet.
