Tuesday, May 1, 2012

I Have some questions on Heat(physics)?

1One way that heat is transferred from place to place inside the human body is by the flow of blood. Which one of the three heat transfer processes best describes this action of the blood? Justify your answer.



2Some animals have hair, the strands of which are hollow, air-filled tubes. Other animals have hair that is composed of solid tubular strands. Which kind of hair would be more likely to give an animal an advantage for surviving in very cold climates? Why?



3 A poker used in a fireplace is held at one end, while the other end is in the fire. Why are pokers made of iron rather than copper? Ignore the fact that iron may be cheaper and stronger.



4Grandma says that it is quicker to bake a potato if you put a nail into it. In fact, she is right. Justify her baking technique in terms of one of the three processes of heat transfer.



5Several days after a snowstorm, the roof on a house is uniformly covered with snow. On a neighboring house, however, the snow on the roof has co



I Have some questions on Heat(physics)?

You know 'justify your answer' sounds like something that it would say on a piece of homework.



Maybe you should do it yourself.



Oh... I'll give you a hint - look up 'convection'.



I Have some questions on Heat(physics)?

1) I would compare it to CONVECTION because a movement of heated material is involved. 2) My guess is the hollow hair as the air in its core would act as an insulator. 3) Consider melting points of Fe and Cu. Also consult a good physics text for a table of Thermal Conductivity. 4) Think CONDUCTION: The nail is conducting the heat into the center of the potato -- and the nail is a better thermal conductor than the flesh of the potato. 5)....collapsed? Slid off? Slope of the roof and surface of roof and temperature of roof surface would all effect the longevity of snow on the roof.



I Have some questions on Heat(physics)?

I won't flat out answer these for you, but I will give you some hints that should help.



1. Well, the three types of heat transfer are a) radiation, b) convection, and c) conduction. It should be pretty obvious that your blood doesn't radiate heat to other parts of your body, that leaves either b) or c). One more hint would be, if your blood did not circulate through your body, do you think you would stay as warm? (disregarding the whole "death" side-effect of such a condition)



2) An animal's fur helps to keep its body heat inside, and not lost to the air by conduction through the skin. So, is air a better or worse conductor of heat than solid fiber?



3) What do you think would happen if you held a copper rod in a fireplace for very long? Would you tell the ER doctor that it was radiation, convection or conduction that burned the crap out of your hand?



4) There is such a thing as a convection oven, and the nail trick wouldn't work as well in one. However, I bet Grandma doesn't have one.

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