Temperature difference. The greater the difference in temperature between the two ends of the bar, the greater the rate of thermal energy transfer, so more heat is transferred. The heat, Q, is proportional to the difference in temperature:
Cross-sectional area. A bar twice as wide conducts twice the amount of heat. In general, the amount of heat conducted, Q, is proportional to the cross-sectional area, A, like this:
Length (distance heat must travel). The longer the bar, the less heat that will make it all the way through. Therefore, the conducted heat is inversely proportional to the length of the bar, l:
Time. The amount of heat transferred, Q, depends on the amount of time that passes, t — twice the time, twice the heat. Here’s how you express this idea mathematically:
Now you can put the variables together, using k as a constant of proportionality that’s yet to be determined.
what does this mean???
Temperature difference. The greater the difference in temperature between the two ends of the bar, the greater the rate of thermal energy transfer, so more heat is transferred. The heat, Q, is proportional to the difference in temperature:
Cross-sectional area. A bar twice as wide conducts twice the amount of heat. In general, the amount of heat conducted, Q, is proportional to the cross-sectional area, A, like this:
Length (distance heat must travel). The longer the bar, the less heat that will make it all the way through. Therefore, the conducted heat is inversely proportional to the length of the bar, l:
Time. The amount of heat transferred, Q, depends on the amount of time that passes, t — twice the time, twice the heat. Here’s how you express this idea mathematically:
Now you can put the variables together, using k as a constant of proportionality that’s yet to be determined.