Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning - Discussion

The correct answer is: iron.

Thermal diffusivity is a measure of how quickly heat spreads through a material. Iron has a high thermal diffusivity due to;

1. High thermal conductivity (ability to conduct heat).
2. High density.
3. Low specific heat capacity (ability to absorb heat).

Iron's thermal diffusivity is approximately 23.1 mm²/s, which is one of the highest among common materials.

The other options have lower thermal diffusivities:

- Lead: 0.24 mm²/s (due to its low thermal conductivity and high specific heat capacity).
- Concrete: 0.14 mm²/s (due to its low thermal conductivity and high specific heat capacity).
- Wood: 0.06 mm²/s (due to its low thermal conductivity and high specific heat capacity).

Note: Thermal diffusivity values can vary depending on the specific material grade, temperature, and other factors.