Consider two cooking pots of the same dimensions, each containing the same amoun
ID: 2068413 • Letter: C
Question
Consider two cooking pots of the same dimensions, each containing the same amount of water at the same initial temperature. The bottom of the first pot is made of copper, while the bottom of the second pot is made of aluminum. Both pots are placed on a hot surface having a temperature of 125°C. The water in the copper-bottomed pot boils away completely in 424 s. How long does it take the water in the aluminum-bottomed pot to boil away completely? (The energy required to heat the base of each pot is negligible compared to the heat required to boil the water. Use 397 J/s · m · °C for the thermal conductivity of copper and 238 J/s · m · °C for the thermal conductivity of aluminum.)Explanation / Answer
Take the thermal conductivity of copper (397) multiply by temperature of surface (125) and multiply by the time it took to boil away completely (424). This will be the total energy required (which will be equivalent for both the copper and aluminum pots). Then set this value equal to the aluminum pot; which you know the thermal conductivity (238) and temperature (125) solve for the time. (397)*(125)*(424) = (238)*(125)*(x) 21041000 = 29750(x) Solve for x: x = 707.26 seconds