PLEASE HELP! I'm doing a physics demonstration, and in part of it I'm trying to explain why steel wool burns and normal steel doesn't. I know it's something to do with the smaller surface area and/or mass but I don't know WHY it burns because of this. Can anyone help me? I'm desperate!

A sheet of steel conducts the heat away from the localized area where the flame is so that the "spot" never gets above the combustion temperature. With steel wool, the surface area is much larger; however, the much smaller size of the wire means heat is conducted away much less (resistance is greater) and the iron does have a chance to become hotter than that necessary to start combustion.

OMG thank you SOOOOOOO much :D

You're welcome! I'm glad I could help clarify the reason why steel wool burns but normal steel doesn't in your physics demonstration.

As you mentioned, the key factor is the surface area and mass of the steel. Steel wool has a much larger surface area compared to a sheet of steel due to its structure consisting of fine, interconnected wires. This means that more oxygen can come into contact with the steel in steel wool.

When you set fire to steel wool, it undergoes a process called oxidation where it reacts with oxygen in the air. This reaction produces heat and light. However, in the case of a sheet of steel, the localized area where the flame is doesn't have enough oxygen readily available to sustain combustion. Additionally, the larger mass and potentially thicker structure of the sheet of steel conducts heat away from the flame, not allowing it to reach the temperature required for combustion.

On the other hand, the smaller size of the steel wool wires means that heat can't be conducted away as efficiently. This resistance to heat transfer allows the iron in the steel wool to become hotter than the combustion temperature, enabling it to ignite and burn.

So, it's not just the surface area and mass that play a role, but also the ability of steel wool to resist heat transfer, allowing it to reach the necessary temperature for combustion.

If you have any more questions or need further clarification, feel free to ask!