Question

two iron rods are placed horizontally, touching end - to - end. one end of one rod is heated. after some time, the other rod also feels warm to touch. how did the heat travel from the heated end to the one that was not heated?
a the air over the heated rod transferred to the other rod and made it warm.
b part of the heat was converted to radiation and traveled to the cooler rod.
c electrons within the rods started moving, distributing heat consistently in both rods.
d the molecular movement in the first rod transferred energy to the molecules in the second.

Explanation:

Heat transfer between solid metal rods in direct contact occurs via conduction. In solids, this happens when molecules in the heated region vibrate more vigorously, transferring kinetic energy to adjacent molecules, which propagates through the material. Option A describes convection (air-based), which is not the primary method here. Option B refers to radiation, which is heat transfer via electromagnetic waves, not direct contact transfer. Option C incorrectly focuses on electron movement, which is more relevant for electrical conduction; thermal conduction in metals involves both electron movement and molecular vibration, but the core mechanism for direct solid contact is molecular energy transfer. Option D accurately describes the conduction mechanism for solids in contact.

Answer:

D. The molecular movement in the first rod transferred energy to the molecules in the second