Mild steel nails were driven through a solid wood wall consisting of two layers, each 2.5 cm thick, for reinforcement. If the total cross-sectional area of the nails is 0.5% of the wall area,...

Mild steel nails were driven through a solid wood wall

consisting of two layers, each 2.5 cm thick, for reinforcement. If the total cross-sectional area of the nails is 0.5%

of the wall area, determine the unit thermal conductance

of the composite wall and the percent of the total heat

flow that passes through the nails when the temperature

difference across the wall is 25°C. Neglect contact resistance between the wood layers.