Cost of tapered candle vs. rate of burn?

[KWB]

Hello Forum!

I hope someone can help me. I have a project due Nov. 9th and I have done 'zero.' I procrastinated, yes. Sadly, I used the 'expected soon' passing of my grandmother as an excuse. She left us on October 20th and I find that my mind is no-clearer than it was before she left. Now I have just about a week before the due date and I'm totally lost. I know there is a lot of information on this site... almost too much for me to deal with and understand with so little time left. I really need help. This is my very first science project and I have no clue. I just want to cry!

I really enjoy candles. Watching the flames flickering allows me to think (I should have spent more time thinking about this project). So, I decided I might do a project concerning the cost of a tapered candle and how quickly it burns. I thought I would first measure each candle and then measure after each burn. But, my Mom thinks I should weigh each candle instead. What do you suggest? What calculation would I use? I mean, would the new, unused candle be worth 100%? I've not weighed them yet, but I guess each one would be slightly different. Then how would I figure all of this? I don't have a hypothesis yet... as I said, zero! My Mom did buy two of each candle for me and a display board. She is upstairs reading the instructions for the project as I am writing this. I finally brought it home today... I don't think Mom is very happy with me.

I really need all the help/assistance/guidance/suggestions you can give. I hope that someone can help me. I was in a panic when I first found this site and signed up. Now I'm feeling even worse. When Mom helped me to register for this site, I thought my question would be posted right away. Yes, she told me that was just for my profile... I had to actually post the questions. Well, I didn't... until now... and almost two more weeks have passed... PLEASE HELP ME! And see my profile too! Thank you. Thank you. Thank you. Oh, and I guess I have to present this to the class also. Oh my... I am in so much trouble.

Thank you so, so much,
Ken

[kgudger]

Hello and welcome to the forums!

The variable that will change will be the weight (Mom gets points for that). However, you should also measure the diameters of the candles. You will measure how much has burnt (versus time, I assume?) by measuring the weight loss. However, the diameter of the candle will matter, too.

I would suggest many more samples than just 2. Many science experiments fail due to a lack of enough samples. Try at least 10 candles per type of candle. Candles especially vary per candle, so you need to get a good average. (In a good trial, you might have 100 items, but that's too many for this level of experiment.)

Good luck and keep us posted on your progress!
Keith

[KWB]

Thank you for the quick reply Keith!

I wasn't very clear... I sorry. Actually, I have a total of 10 candles. I have two of each type/cost... five different sets... five different colors. I wasn't sure if I needed to keep one of each as an example and one of each to burn. They are all the same diameter and all are the bell-shaped tapers (the same diameter for the entire length... just the very top is kind of pointed - bell shaped). They are not the usual tapers that are thicker at the base and thinner at the top. I guess they shouldn't be called tapers!

I have two sets that are 11", two sets are 10", and one set is 8". Can you give me an idea of the mathematical equation I would use to calculate the percentage of the weight of the candle that was burned? Initially, regardless of their size or weight, they all start at 100% - right? How much burn time would you suggest between each measurement? How would the diameter play into the equation? (I also have a set of the 'usual tapers' that I decided not to use because they are a shiny gold color. They seem to have some kind of outside covering rather than just the candle wax throughout. I'm already confused enough and that just seemed way too different.)

Thank you again,
Ken

P.S. I have some more questions, but Mom says I'm so 'wordy' that some of my concerns get missed. So, I'll wait for a response to this post first... then I'll post some more! Thank you so much!!!!!!!

[kgudger]

Hi Ken:

It seems to me that you are looking at the burn rate vs. the cost or color or ???. You need to pick a dependent variable and an independent variable. Have you seen the Science Buddies guildelines? https://www.sciencebuddies.org/science- ... bles.shtml

You will probably want to burn each candle for 10 minutes to an hour - pick the time before you start your experiment. To see how much of the candle burns, you would weigh the candle before the burn and after, and calculate the difference as the weight of wax burned. You do not want to measure a percentage, but an absolute weight change. A good kitchen scale will work. Also, try to estimate the volume of the wax burned. You would measure the diameter of the candle and the length burned away (Volume (of a cylinder) = (pi) * r(squared) * h ). You might want to plot your data versus weight r volume - I don't know which will work better, but you can try both! The fun of experimentation is that you don't always know the answer ahead of time

Keith

[KWB]

Keith, Thank you so much for all the help. It is Sunday and my project is due Tuesday... yikes! I am now on my third edit... it's 12+ hours since my post early this morning... am I not adding to my original post correctly? (I'm really nervous... and in need of more guidance... PLEASE...thank you)

Okay, I am now in the process of burning (the second trial). I chose to burn the candles at 1 hour intervals. I am lighting them and 'snuffing' them at 5 second intervals. I am weighing them after each burn. I have a total of 10 candles (5 different brands/costs - two of each). I am burning 5 candles during each 1 hour session. I figured I will do this twice... not enough time for more than two trials. I have one 8", two 10" and two 12" candles (two of each). I am weighing in grams. I did not measure the diameter. I was hoping that the weights would be enough to come up with a table and graph (which I really need help with). I have each of my candles in small crystal holders. I identified them with 1A, 2B, 3C, 4D and 5E. I am burning the first set of five (1 thru 5). The second duplication of the experiment will be A thru E. I weighed each individual candle (which I also identified in the same manner) and each corresponding holder. Following each one hour burn, I am weighing both the holder and candle together and will substract the holder weight from the number. I'm not sure I understand when I should stop the final burn. I made a mark on each candle, 1 1/2" from the bottom of each candle. This is basically the top of the holder. Should I shop the burn when it hits that mark or should I let it continue for the full hour? There would be enough wax and wick remaining below the line and room in the holder to do this... this would be okay. Trying to stop at the mark could be difficult. Some of the candles are burning 'at an angle'... I think I have them protected from drafts though. So, whereas the mark may be reached at one point, the opposite side of the candle may still be 1/4" away. I hope this makes sense!

I really need to know if what I have done here is good enough. I really could use your comments on what I have written and any further suggestions on how to complete this! I'm still unsure about the variables. Would this be right...? The independent variable = the cost of the candle; the dependent variable would be the candle weights at each 1 hour interval or the wax burned/lost; and the controlled variables would be the five different brands of candles... or is this the same as the individual cost of each candle? I am sooooo confused and really need lots of help. I have the sample of the graph & table, guess I'm just not 'getting it' when it comes to setting it up and putting things where they belong! Please help me with the table and graph, if you would be willing. I have the cost of each individual candle, I will have the beginning weights and the weights after each 1 hour burn. Let's see, what else do I have? HELP! Thank you again, KWB (P.S. Keith, Why wouldn't I want to look at the percentage of the weight lost? I thought this we be a good thing!) THANK YOU, Ken

[kgudger]

Hi Ken:

Lot's of questions! I'm not sure I understand how you're weighing the candles, but whether the holder is included doesn't matter as long as it's included in both before and after measurements. You're looking for the mass of candle wax burned, so you're interested in the difference in the two measurements.

You asked about why the percent doesn't matter. What you're measuring is the amount of fuel consumed for each candle type to burn a set amount of time. This is like miles per gallon in your car. Your gas gage tells you how full your tank is - this is like the percent of fuel left. However, to compare two cars, you wouldn't look at how full the tank is, but at their fuel efficiency - miles per gallon - to compare them.

If your candles are burning all the way down to the holder, you need to stop there. Just record the time burned and the mass burned. Your final measurement is time versus mass burned. It sounds like you can get a quantitative comparison of the different candles this way.

Keith

[KWB]

Thank you Keith!! The question of % makes sense to me now. Thanks for taking the time to read through my panic! I was taking a break from working on the board and thought I'd check to see if you had responded... I'm glad I did. I think I have done things right. At least I hope so! Your answers helped a lot. Thank you so much. I'll have to let you know how the class grading goes... and maybe upload a picture! Thanks so much for all your help. I really did appreciate it. Well, Mom's calling me. It's midnight now. I'm going to be tired tomorrow! Ken