Two pots are identical, except that in one case the flat bottom is aluminum and
ID: 1498648 • Letter: T
Question
Two pots are identical, except that in one case the flat bottom is aluminum and in the other it is copper. Each pot contains the same amount of boiling water and sits on a heating element that has a temperature of 155 °C. In the aluminum pot, the water boils away completely in 337 s. Concepts:
(i) Is the heat needed to boil away the water in the aluminum-bottom pot less than, greater than, or the same as the heat needed in the copper-bottom pot? less than greater than the same
(ii) One of the factors in the equation Q = (kAT)t L that influences the amount of heat conducted through the bottom of each pot is the temperature difference T between the upper and lower surfaces of the pot's bottom. Is this temperature difference for the aluminum-bottom pot less than, greater than, or the same as that for the copper-bottom pot? less than greater than the same
(iii) Is the time required to boil away the water completely in the copper-bottom pot less than, greater than, or the same as that required for the aluminum-bottom pot? less than greater than the same
Calculations: (a) Find the time it takes the water in the copper-bottom pot to boil away completely.
Explanation / Answer
i) heat needed to boil away the water in the aluminum-bottom pot is greater than heat needed in the copper-bottom pot . Because copper has greater thermal conductivity than aluminium .
ii) temperature difference for the aluminum-bottom pot is less than, that for the copper-bottom pot .
iii) time required to boil away the water completely in the copper-bottom pot is less than, as that required for the aluminum-bottom pot .
a) the time it takes the water in the copper-bottom pot to boil away completely = (237/401) * 337
= 199.17 sec
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