I was lighting candle yesterday, and also was trying to make the match last for as long as I could without burn my fingers. I noticed the the speed at which the flame evolved along the match was dependence on the edge at which I hosted the match.As you have the right to see in the video, once the complement points contempt downward, the fire travels conveniently along the match. When it points contempt upward, this progression is slowed. When the enhance is vertical, the flame goes the end altogether. To do the match last as lengthy as possible, I desire to keep it ideal on the edge of walk out, yet without actually doing so.

You are watching: How long does a match burn


To perform this I develop a mental feedback loop to increase the angle from vertical when the complement flame is too small, and to diminish it once the flame is as well large. In this post, I"d prefer to explore that feedback loop.
To begin, lets define some geometry. We"ll assume the complement is 1 dimensional, and has its beginning at the head that the match, with the x measurement increasing together you move away from the head. As the flame progresses along the match, the flame has a front, which we define as the location of the an initial bit the unburnt match you have the right to see beside the flame, and also a rear, i beg your pardon is unburning char.
*

*

1) when a ar of match is lit, it will certainly burn because that a continuous amount of time, nevertheless of the angle "a".
2) unburnt hardwood pyrolyzes at a rate inversely proportional to the square that the distance from the flame
We require to know the relationship in between the edge at i beg your pardon the match is held, and also the characteristics distance between the flame and also the unburnt part of the match:
*

*

where r is a characteristic dimension of the flame, i m sorry we"ll i think to be constant. The flame breakthrough rate is then:
*

where b is the overall consistent of proportionality, and delta is an offset that accounts for the thickness the the match. To get the experimental constants, we"ll measure up the rate of development up the match, and also fit a curve to the data. Here are the experiments:
In these images the upright distance between the two lines is the dimension of the fire at any given point in time, and the horizontal distance between the lines is the moment it takes any given suggest along the match to ignite, burn, and extinguish itself.
The flame price is the average slope of the "front" curve in each image before it will the end of the match. We can plot this data points and also fit a curve based upon the theoretical equations above, and also solve for the speculative parameters "b" ~ .025 and also "delta" ~ 20 degrees:
Now that course, these parameters are distinct to ours matches, in our environment, and will probably need to change with the circumstances, however this is in ~ least sufficient to gain us started.
From the graphs the our experiments we also estimate the time a given part of the match spends burn as about 5 seconds, and the minimum flame size to sustain burning as 3/16ths of an inch. The not important for united state to be super precise, together we"ll be looking at trends and behaviors in our model, and also because each type of match will behave differently.

See more: Rising Warm Air Transports Thermal Energy By, Chapter Test Flashcards


In the next article on this topic, we"ll construct a design of our device using the parameters we estimated here, and also see if we can recreate the it was observed behavior.