Which type of heat transfer occurs when one end of a steel beam is exposed to heat and the other end begins to heat up?

The correct answer is conduction because this type of heat transfer occurs through direct contact and transmission of heat from one molecule to another. When one end of a steel beam is exposed to heat, the molecules at that end gain energy and begin to vibrate more vigorously. These energized molecules then pass their heat energy along to adjacent molecules in the beam, causing the heat to move from the heated end to the cooler end.

This phenomenon is particularly relevant in solid materials like steel, where atoms are closely packed and can transfer kinetic energy efficiently. Unlike radiation, which involves the transfer of heat through electromagnetic waves and does not require a medium, or other processes that do not represent direct contact or simple thermal transfer, conduction is the principal mode of heat transfer in solids.

By understanding conduction, firefighters can better assess the risks of structural weakening in steel beams and other materials during a fire.