Why do smaller pieces of wood burn faster?
I take it you mean faster than large pieces of wood.
In essence it is down to the larger surface area to volume ratio of the smaller piece of wood. If we had a 1 metre cube of wood the surface area is 6 m^2 and the volume is 1 m^3. If we divided this into 8 equal cubes, each cube is now 1.5 m^2 (6 x0.5 m x 0.5 m) in area so the total is 12 m^2 and the volume is still 1 m^3.
Thus the air sees a much larger surface area and the wood will burn faster than the original cube.
If we continue this until we reach saw dust we have a very large surface area indeed. So much so that saw dust in air will burn so fast that it can cause an explosion.
There is quite a good demonstration on YouTube search for "Jake's Attic - Saw Dust Explosion"
basically.......cause there is less of it to burn... :)
Smaller pieces of wood burn faster due to a few factors. To understand why, let's consider the concept of surface area-to-volume ratio. When wood burns, it undergoes a chemical reaction with oxygen in the air, producing heat, light, and various byproducts. The burning process occurs at the surface of the wood.
A smaller piece of wood has a larger surface area compared to its volume, meaning there is more exposed surface area for oxygen to react with. As a result, more oxygen can reach the wood and participate in the burning process. This increased availability of oxygen accelerates combustion, leading to a faster burn rate.
Additionally, smaller pieces of wood have a relatively lower mass, which means they require less heat energy to reach their ignition temperature. This allows them to catch fire more quickly, enhancing the overall burning speed.
Overall, the combination of increased surface area-to-volume ratio and lower mass contributes to smaller pieces of wood burning faster than larger ones.