The heat from the bonfire is transferred to the student's hands mainly, but not exclusively, through the process of RADIATION.
There are three mechanisms or processes of heat transfer: conduction, convection, and ratiation.
Conduction is carreid out by contact; it requires that the two objects are touching each other. This is not the case.
Convection is the heat transferred by the movement of the fluids (liquids ang gases). In some extent this happens in this case, but it is not the dominant effect becasue air is not a very good conductor. Specially if there is not much air movement (wind).
Thermal radiation is carried out by electromagnetic waves. When there is a source of intense heat, like the fire, the heat is propagated by radiation.
Then really, the heat from the bonfire gets to the student's hands by convection and radiation, but as fire is very intense (its temperature is very high), and as long as the air is calmed, the dominant process is radiation. If there is wind, convection starts to be important.
Answer:
The theory of evolution by natural selection, first formulated in Darwin's book "On the Origin of Species" in 1859, is the process by which organisms change over time as a result of changes in heritable physical or behavioral traits. Changes that allow an organism to better adapt to its environment will help it survive and have more offspring.
Evolution by natural selection is one of the best substantiated theories in the history of science, supported by evidence from a wide variety of scientific disciplines, including paleontology, geology, genetics and developmental biology.
The theory has two main points, said Brian Richmond, curator of human origins at the American Museum of Natural History in New York City. "All life on Earth is connected and related to each other," and this diversity of life is a product of "modifications of populations by natural selection, where some traits were favored in and environment over others," he said.
More simply put, the theory can be described as "descent with modification," said Briana Pobiner, an anthropologist and educator at the Smithsonian Institution National Museum of Natural History in Washington, D.C., who specializes in the study of human origins.
The theory is sometimes described as "survival of the fittest," but that can be misleading, Pobiner said. Here, "fitness" refers not to an organism's strength or athletic ability, but rather the ability to survive and reproduce.
Answer:
lithosphere
Explanation:
is found under the oceans and formed at spreading centres on oceanic ridges, which occur at divergent plate boundaries.
Answer:
they now also believe that earth is 6000 years old
Explanation:
3) IT INFLUENCES THE DEVELOPMENT OF ADULT SEX CHARACTERISTICS.
Estrogen is the primary female sex hormone. They promote the development of primary and secondary sex characteristics in females. These characteristics include breasts, uterus and vagina at puberty.
They are also involved in regulation of the menstrual cycle. Estrogen causes ovum (egg) maturation and follicle development, development of endometrium (lining of a uterus) during the proliferation phase of the uterine cycle.
