Exploring Heat Transfer Principles

[UNknown 2010]

Hello,

I hope this is the right place.


Which of the following is false?
a. Convection only takes place in gases and fluids.
b. Heat radiation can take place across a vacuum.
c. A perfect radiating surface has an emissivity (e) = 1.
d. A perfect heat insulator has an emissivity (e) = 0.
e. Water is a better heat insulator than air.

Which of the following statements is false? Heat loss mechanism is done
a. By increasing conduction and radiation from the skin
b. By increasing sweating rate
c. Through increasing blood flow near the skin surface
d. Through counter current exchange.
e. By Reducing the metabolism

Heating 200 g of water for 1 minute, the water temperature rises from 10 oC to 18 oC . Heating 400 g of water at 10°C with the same amount of heat for 1 minute, what would you expect the final temperature to be?
Choose one answer.
a. 10 oC.
b. 12 oC
c. 14 oC.
d. 16 oC
e. 18 oC

For an astronaut working outside a spaceship, the greatest loss of heat would occur by means of
Choose one answer.
a. conduction.
b. convection
c. conduction and convection.
d. radiation.
e. None of the above

Which of the following is true?
a. Thermoregulatory system acts to facilitate heat loss in hot environment.
b. Thermoregulatory system acts to facilitate heat loss in cold environment.
c. Thermoregulatory system acts to facilitate heat gain in hot environment.
d. Thermoregulatory system acts to increases metabolism in hot environment.
e. Thermoregulatory system acts to decreases metabolism in cold environment.





Are all my answers are correct ?

 

[Andrew Mason]

They all look correct to me.

AM

 

[tomcue]

Hello,

I am happy to see your interest in exploring heat transfer principles. To answer your questions, I would like to provide the following responses:

1. The false statement is d. A perfect heat insulator has an emissivity (e) = 0. A perfect heat insulator would have an emissivity of 1, as it would not allow any heat to pass through it.

2. The false statement is e. By Reducing the metabolism. In fact, reducing metabolism would slow down the body's heat production, leading to a decrease in heat loss.

3. The final temperature would be 14 oC. The amount of heat required to raise the temperature of water by a certain degree is directly proportional to its mass. Therefore, heating 400 g of water would require twice the amount of heat as heating 200 g, resulting in a final temperature of 14 oC.

4. The greatest loss of heat for an astronaut working outside a spaceship would occur by means of d. radiation. In the vacuum of space, there is no medium for convection or conduction to take place, leaving radiation as the only means of heat transfer.

5. The true statement is b. Thermoregulatory system acts to facilitate heat loss in cold environment. In cold environments, the body's thermoregulatory system works to conserve heat and prevent heat loss, such as by shivering and vasoconstriction.

I hope this answers your questions and helps clarify any doubts. Keep exploring heat transfer principles!