3. We wish to determine the thermal conductivity of an apple (= 950 kg/m3, Cp =...

3. We wish to determine the thermal conductivity of an apple (= 950 kg/m3, Cp = 3200 J/kg K), which can be considered to be a sphere of radius R = 4 cm. To do this, we design an experiment in which a thermocouple is placed at the center of the apple. A rubber sphere of known properties (= 980 kg/m3, Cp = 1910 J/kg K, k = 0.17 W/m K) and the same radius (4 cm) is also provided with a thermocouple placed at its center. Both the apple and the rubber sphere are initially at 25 °C and they are immersed simultaneously in a perfectly-mixed water bath at 75 °C. After a certain time has passed, the two thermocouples read: Apple: 72 °C, rubber sphere: 45 °C. (a) Determine the thermal conductivity of the apple and the time at which the temperature readings were taken. (b) How much thermal energy (J) has been removed from the water bath during this process?

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Amanda K answered 1 week ago

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