Thermal Energy Transfer: Question 5
Syllabus 2.3.1
A metal fire poker has one end resting in the glowing embers of a campfire for several minutes. The other end, which never touches the embers or the flames, is being held by a camper wearing a thick glove. The camper notices that this held end slowly becomes hot.
Which statement correctly explains how thermal energy travels along the solid metal poker, from the end in the embers to the end being held?
Show worked solution Hide worked solution
Worked solution
Step 1: Recall what conduction is
Conduction transfers thermal energy through a material without the material itself moving from place to place. It happens because of the vibration of particles that stay in fixed positions within the solid.
Step 2: Follow the energy from the hot end
At the end resting in the embers, particles absorb thermal energy and vibrate more vigorously about their fixed positions. Each particle is bonded to its neighbours, so as it vibrates more it collides with them and passes on some of this extra vibrational energy.
Step 3: Continue the chain along the poker
Each neighbouring particle, having gained energy, vibrates more itself and passes energy on to its neighbours in turn. This chain of collisions continues all the way along the solid metal poker, gradually carrying thermal energy from the hot end to the end being held, even though no single particle travels any distance at all.
Step 4: Match to the correct option
This particle-vibration-and-collision description is exactly option B.
Why the other options are wrong
| Option | Error |
|---|---|
| A | Particles in a solid do not travel from place to place; they stay in fixed positions and vibrate. Particles physically moving and carrying energy with them describes convection in a fluid, not conduction in a solid. |
| C | Conduction relies entirely on energy passing between neighbouring particles; it cannot skip past the particles of the solid. |
| D | A solid conducts thermal energy perfectly well without melting; the poker stays solid throughout, and conduction still occurs via vibrations. |
Final answers
- Thermal energy travels along the poker by particles vibrating more and passing this extra vibration on to their neighbours through collisions, option B.