Question

Calculate the amount of heat conducted in 45 min through an iron plate 5-cm thick and with an area of 2 sq m. The two sides are kept at 0°C and 60°C. (Kfc=0.12)

Answer 1

Answer on Question #39678, Physics, Mechanics

Question:

Calculate the amount of heat conducted in 45 min through an iron plate 5-cm thick and with an area of 2 sq m. The two sides are kept at 0°C and 60°C. (Kfc=0.12)

Answer:

Amount of heat equals:

$$Q = \frac {K _ {f c} A \Delta T}{d} t$$

where $A$ is area, $d$ is thickness, $K_{fc}$ is thermal conductivity of iron, $\Delta T$ is temperature difference, $t$ is time.

Therefore:

$$Q = \frac {0 . 1 2 \frac {W}{K \cdot m} \cdot 2 m ^ {2} \cdot 6 0 {}^ {\circ} C}{0 . 0 5 m} 4 5 \cdot 6 0 s = 7 7 7 6 0 0 W \cong 7. 8 \cdot 1 0 ^ {5} W$$

(But it looks like mistake in thermal conductivity, because its value for iron is about 70 - 80 $\frac{W}{K \cdot m}$ . Then:

$$Q = \frac {7 5 \frac {W}{K \cdot m} \cdot 2 m ^ {2} \cdot 6 0 {}^ {\circ} C}{0 . 0 5 m} 4 5 \cdot 6 0 s \cong 5 \cdot 1 0 ^ {8})$$