- #1
moatasim23
- 78
- 0
A person is standing near heater .How is he getting heat?
gmax137 said:Both. Plus, some conduction through the air.
Born2bwire said:I would think that conduction by air is mostly just another way of saying convection in this case since the heated air will flow from the heater to the person, very little actual conduction will be taking place. I think you would have to assume a more or less uniform room temperature for the heat transfer from the air to be conduction.
boneh3ad said:Movement of air as a result of temperature differences is a result of buoyancy, so the forces are parallel to gravity. Sure, in this case the fluids are arranged so that the strata are unstable and you would end up with horizontal movement that way, but all that hot air would end up heading upward anyway. It is an oversimplification to say that the air will move from the heater to the person in general.
Also, with a uniform room temperature distribution, the heat transfer would be zero. You can't transfer heat without a temperature difference.
moatasim23 said:It came in my test as Multiple Choice Question and there was no option for ALL.So i expect it has some definite answer.Please help me sort it out.Bcz it is confusing me.Thanks
Born2bwire said:The movement of heated air in a room does not generally just float up, due to the confinement of the room it will disperse about the ceiling and so forth plus there are the existing airflows in a room brought about from the ventilation system and pressure differences. But if you have a uniformily heated environment, then there isn't going to be much flow of heat due to the air currents. So anyone stepping into the room and absorbing heat (or cooling off) will probably experience more conduction heat transfer.
Either way, this is meant to be a simplification because it appears to be high school level at most.
jetwaterluffy said:Probably what it should have said was how is he mostly getting heat, then. And the answer would be convection. Radiation is slow.
Not really. Look at how dimly glass or metal glows when heated to ridiculously hot temperatures. That is the only way the energy is getting out. Convection may be slow, but radiation is slower still.moatasim23 said:How could it be?I thought convection was slow bcz in it the air has first to be heated and then rise up.So that convection cycle starts and the room gets heated up.In this way he gets heat.While through radiation he will get heat directly.Isnt it so?
jetwaterluffy said:Not really. Look at how dimly glass or metal glows when heated to ridiculously hot temperatures. That is the only way the energy is getting out. Convection may be slow, but radiation is slower still.
Convection refers to the transfer of heat through the movement of fluids or gases, while radiation is the transfer of heat through electromagnetic waves.
Convection is typically more efficient than radiation as it can transfer heat over larger distances and can be controlled more easily through the use of fans or pumps.
In the atmosphere, convection occurs through the movement of air masses due to differences in temperature and pressure. Warm air rises, while cool air sinks, creating convection currents.
Yes, in many cases both convection and radiation are occurring simultaneously. For example, in a heating system, radiation may transfer heat to objects in a room while convection moves the warm air around.
Convection plays a crucial role in weather patterns, as it is responsible for the formation of clouds, precipitation, and wind. Warm air rising and cool air sinking creates pressure differences that drive weather systems.