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sgstudent
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I learned that solids conduct heat by vibrating and thus transferring the energy from one particle to another particle. However, my teacher gave us a question: two metal rods of different material are placed in a fire. one of them turns red hot at the end while the other remains silver coloured throughout. which one feels hotter she explained that the one they does not glow is able to conduct the best as for normal by lattice vibrations and the movement of electrons. while the other one accumulates the heat so the thermal conductivity of that rod is lesser as compared to the one that remained silver. so the heat will accumulate at the end and it is observed as the red hot part. is this correct?
So what happens when I remove both of them from the fire? Since no more best is provided will the silver one radiate heat to the surrounding area for the totally silver one so it will drop in temperature. then what about the metal rod with the red hot end? Will the heat energy from the red hot end be conducted to the entire metal rod before radiating the heat? how will the heat travel? Will it reach an equilibrium before radiating or will the process occur simultaneously where it is being radiated out and the heat also flows by conduction.
I think it should occur simultaneously but I'm still confused about this.
also, when an object is a bad conductor of heat, once it reaches its limit of thermal conduction will the heat accumulate at one place and get heated up. so if a wooden rod can only transfer 10J of energy per unit time once it exceeds that amount will the exceeded amount be retained as heat being accumulated at that point. eg 15J is provided per unit time so every unit time 5J of heat is accumulated until it burns or melt?
Lastly, for thermal radiation, how do I tell if an object is emitting radiant heat or absorbing it? At first I thought it was to determine the object in question to the surrounding. If it is hotter as compared to the surroundings it is emitting and if opposite, then it is absorbing heat. But in a textbook example they seem to work both ways. For the absorbing radiation's explanation this is what they face: two aluminium foil are connected to data loggers. One of them is blackened. The blackened one absorbed radiation at a faster rate as compared to the shiny one. Hence, black surfaces absorb infrared radiation faster than shiny ones.
For the emitting one this is what they gave: a black tin and white tin is filled with boiling water, also data loggers are placed on the top of the two tins. The temperature drop for the black tin is faster than the shiny tin.
Aren't they repeating the same experiment just in different manner? And even worse I can't tell whether they are trying to refer it to absorption or emission of the radiant heat. I'm hoping that you awesome geniuses can help me find a way to determine which one occurs when a question is thrown st me. Thanks for the help guys!
So what happens when I remove both of them from the fire? Since no more best is provided will the silver one radiate heat to the surrounding area for the totally silver one so it will drop in temperature. then what about the metal rod with the red hot end? Will the heat energy from the red hot end be conducted to the entire metal rod before radiating the heat? how will the heat travel? Will it reach an equilibrium before radiating or will the process occur simultaneously where it is being radiated out and the heat also flows by conduction.
I think it should occur simultaneously but I'm still confused about this.
also, when an object is a bad conductor of heat, once it reaches its limit of thermal conduction will the heat accumulate at one place and get heated up. so if a wooden rod can only transfer 10J of energy per unit time once it exceeds that amount will the exceeded amount be retained as heat being accumulated at that point. eg 15J is provided per unit time so every unit time 5J of heat is accumulated until it burns or melt?
Lastly, for thermal radiation, how do I tell if an object is emitting radiant heat or absorbing it? At first I thought it was to determine the object in question to the surrounding. If it is hotter as compared to the surroundings it is emitting and if opposite, then it is absorbing heat. But in a textbook example they seem to work both ways. For the absorbing radiation's explanation this is what they face: two aluminium foil are connected to data loggers. One of them is blackened. The blackened one absorbed radiation at a faster rate as compared to the shiny one. Hence, black surfaces absorb infrared radiation faster than shiny ones.
For the emitting one this is what they gave: a black tin and white tin is filled with boiling water, also data loggers are placed on the top of the two tins. The temperature drop for the black tin is faster than the shiny tin.
Aren't they repeating the same experiment just in different manner? And even worse I can't tell whether they are trying to refer it to absorption or emission of the radiant heat. I'm hoping that you awesome geniuses can help me find a way to determine which one occurs when a question is thrown st me. Thanks for the help guys!
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