Question

1. A Styrofoam box (k=0.01 J/(s*m*C) containing ice water at 0 C has a total area of 0.950m^2 and walls with thickness 2.50 cm in a 35 C room. What is the heat flow through the walls?1. 13.3 W2. 0.133 W3. 0.147 W4. 14.7 W

Answer 1

Step-by-step explanation:

The heat flow can be calculated as

`Q=kA(T_1-T_2)/(L)`

Where k is the thermal conductivity, A is the area, T1 is the temperature of the ice water, T2 is the temperature of the room, and L is the thickness.

Replacing k = 0.01 J/(s m °C), A = 0.950 m², T1 = 0°C, T2 = 35 °C and L = 2.50 cm = 0.025 m, we get

`\begin{gathered} Q=(0.01\frac{J}{s\text{ m }\degree C})(0.95\text{ m}^2)\frac{0\degree C-35\degree C}{0.025\text{ m}} \\ \\ Q=-13.3\text{ W} \end{gathered}`

Therefore, the heat flow through the walls is 13.3 W.

The negative sign indicates the direction of the heat flow, in this case, the heat goes to the water.