How would the rate of heat transfer between a thermal reservoir at a higher temperature and one at a lower temperature differ if the reservoirs were in contact with a 10 -cm-long glass rod instead of a 10 -m-long aluminum rod having an identical cross-sectional area?

Short Answer

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Question: Compare the heat transfer rate between two thermal reservoirs when they are connected by a glass rod and an aluminum rod, both having the same length and cross-sectional area. Answer: The heat transfer rate of the glass rod is only about 0.39% of the aluminum rod. Therefore, the rate of heat transfer is significantly lower when using a glass rod compared to an aluminum rod, with the same cross-sectional area and length.

Step by step solution

01

Understand the Formula for Heat Transfer via Conduction

We need to use the formula for heat transfer through conduction. The formula is given by: Q = (k * A * (Th - Tc) * t) / L Where Q is the heat transfer, k is the thermal conductivity of the material, A is the cross-sectional area, Th is the higher temperature, Tc is the lower temperature, t is the time period for which the heat transfer occurs, and L is the length of the rod. In this exercise, we are concerned with comparing heat transfer rates (Q/t). Therefore, we can simplify the formula as follows: Q/t = (k * A * (Th - Tc)) / L
02

Find the Thermal Conductivities of Glass and Aluminum

We need to know the thermal conductivities of glass and aluminum to calculate the heat transfer rates. The general values for the thermal conductivities are: k_glass ≈ 0.8 W/(m·K) k_aluminum ≈ 205 W/(m·K)
03

Compare Heat Transfer Rates for Glass and Aluminum Rods

Let's denote the heat transfer rates of glass and aluminum rods as Q/t_glass and Q/t_aluminum, respectively. To compare the heat transfer rates of the two rods, we can put the values from Step 2 into the simplified formula from Step 1: Q/t_glass = (k_glass * A * (Th - Tc)) / L_glass Q/t_aluminum = (k_aluminum * A * (Th - Tc)) / L_aluminum Given that the cross-sectional area (A), temperature difference (Th - Tc), and lengths of the rods (L_glass = L_aluminum = 10 cm = 0.1m) are identical, we can find the ratio of the heat transfer rates: (Q/t_glass) / (Q/t_aluminum) = k_glass / k_aluminum Plug in the values for the thermal conductivities: (Q/t_glass) / (Q/t_aluminum) = 0.8 / 205 = 0.0039 Therefore, the heat transfer rate of the glass rod is only about 0.39% (0.0039 * 100) of the aluminum rod. In conclusion, the rate of heat transfer between the thermal reservoirs would be significantly lower when using a glass rod compared to an aluminum rod, with the same cross-sectional area and length.

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