Science Buddies: "Ask an Expert"

I'm so excited to this topic even though I know for sure that I'm not going to win any prize this time because the outcome is obviously predictable.
Anyhow, I'm trying to think of ways to make this experiment more interesting.
In this project, I'm gonna wrap a color piece of paper around a jar filled with water (@ room temp), and then expose the jar under a hear lamp for a while.
Then take the new temperature to see which color absorb most heat.
I'm thinking about mixing the colors to make it more interesting.
But do you have any other idea????
thanks a lot.

It may prove difficult to detect variations caused by the color wrapping the jar.

There are a few problems with this proposed procedure - let me see if I can explain.

Also if you think about it, what you're really describing is the paper heating up, and transferring energy to the water through the side of the jar. To do this, the paper has to heat up, it has to heat the jar, and the jar has to heat the water.

In practice this won't work well, because the paper is a poor conductor of heat. A glass jar is only a medeocre conductor of heat. Water needs a fair amount of energy to increase in temperature even one degree, especially if you are talking about something the size of a soda can as opposed to a few cubic centimeters of water.

To get an idea of the difference between something with good heat conduction and something with bad heat conduction, consider reaching into an oven. Your hand doesn't burn because your hand is mostly made of water, and also has a bunch of means of moving heat around before tissue burns (your blood, sweat, etc).

If your hand brushes against a metal rack though, you burn right away. The metal rack is a good heat conductor.....it's a lot hotter than your hand, and it is good at making your hand as hot as it is, much better at this than air is.

Another way to think about it is consider a cold soda in an aluminum can, versus the same soda poured into a styrofoam cup. Hold the can and your hand will get cold. Hold the cup and it won't. Given that hot coffee can be stored in a paper cup, and a person can hold onto it with only an additional thin cardboard layer (or a second cup), your idea of heating up construction paper and expecting the water to heat up is not very likely to work.

If I was trying to heat water by heating the container, I'd want the container to be something made of metal, so that if it does heat up, the water will heat up too.

There is an additional problem too - a heat lamp can heat up your jar in two ways. One is the way you are trying to measure - the light hits the jar, it's absorbed and turned into heat. The other is a way you don't want to measure - the air around the jar heats up, and warms the jar (like an oven).

The only way to be sure of not getting the second effect would be to do the experiment in a vacuum (someplace with no air) which is probably not practical.

If you could somehow directly measure the temperature of the paper itself (or anything else that you could color), most of the problems go away. You still have to worry about getting an effect that is larger than the "oven effect" - where the radiant heat from light absorbtion causes enough extra heat than that caused just by the air around the lamp/paper getting warm.

Have you talked this over with your instructor? He might have some ideas that address the problems I've raised here. I'm very interested to see if you can find a way to overcome them.

What grade are you in? It will help us to know how much math and thermodynamics to introduce in our help.

I'm not going to win any prize this time because the outcome is obviously predictable.

I'm glad you think it is obvious because you might be in for some surprises. Radient heat is well below the visible light spectrum (even below what is typically considered infrared) and my eyes can't look at a "filter" and tell me how translucent or opaque it is to heat.

The heat lamp will also be heating up the air, the jar, whatever the jar is setting on. Convection currents will occur as well. If the jar is open, water will be evaporating and the evaporation will be cooling the remaining water and the jar and whatever the jar is setting on. The rate of evaporation will be a function of temperature and convection currents. If the radient heat is hitting the jar after if passes through your paper filter, then the jar material will be acting as another filter. If the jar is closed, then the lid is yet another filter.

You can learn a lot about thermodynamics and how to figure out which effects dominate and how to alter the setup to minimize these effects you don't want to influence your experiment with some fairly simple setups.

Craig_Bridge wrote:What grade are you in? It will help us to know how much math and thermodynamics to introduce in our help.

I'm not going to win any prize this time because the outcome is obviously predictable.

I'm glad you think it is obvious because you might be in for some surprises. Radient heat is well below the visible light spectrum (even below what is typically considered infrared) and my eyes can't look at a "filter" and tell me how translucent or opaque it is to heat.

The heat lamp will also be heating up the air, the jar, whatever the jar is setting on. Convection currents will occur as well. If the jar is open, water will be evaporating and the evaporation will be cooling the remaining water and the jar and whatever the jar is setting on. The rate of evaporation will be a function of temperature and convection currents. If the radient heat is hitting the jar after if passes through your paper filter, then the jar material will be acting as another filter. If the jar is closed, then the lid is yet another filter.

You can learn a lot about thermodynamics and how to figure out which effects dominate and how to alter the setup to minimize these effects you don't want to influence your experiment with some fairly simple setups.

I'm in 10th grade; doing Honor Precal and integrated science 3-4. I haven't exposed to the idea of thermodynamics.
Thanks 4 your explanation. It's really help making my experiment more accurate.
But I still can't think of how to make my topic more INTERESTING!!

I'm not sure about interesting/exciting, but how about relavant? Insulation and radient heat barriers affect the efficiency of heating our homes and a variety of other household products (dishwashers, refrigerators, water heaters). Similar issues exist in industrical processes, and then there more exotic applications like the space program.

After researching some basic heat transfer (conduction, convection, and radiant) so you understand a bit more about the area of thermodynamics, you might be able to come up with a hypothesis that might be more interesting or relavant. Then figuring out how to conduct an experiment might lead in a slightly different direction.

A lot depends on whether you want to focus on heat, or whether you want to focus on radiant energy vs color.

The latter is going to be challenging to do with the tools you have.

There are a lot of things you can do oriented around heat conductance that can be very interesting and relevant to your life.

For example, did you know that leaving the refrigerator door open will actually heat up the kitchen, rather than cool it?

Do you know that turning on the heater in a car (the kind that blows air, not things like warm seats) can help prevent a car engine from overheating?

The kitchen is full of stuff involving heat transfer - there is a reason why you want to grill or fry some food, and bake other foods, and why different kitchen implements have different handles or are made of certain materials.

A thermos can keep drinks cold or keep them hot. A hot pan will cool much faster immersed in water than left out in the air. Water at boiling temperature will burn you, a wood cutting board at boiling temperature will not.

Find a question that relates to real life, then form a hypothesis on why it behaves that way and do an experiment to prove it. By relating your experiment to the real world, that's how you make it "cool".

(My best student research project ever was when I studied formations of traffic jams on Los Angeles freeways. I got the idea while driving with a friend on the way to another college to see some friends and we wondered why traffic jams moved the way they did, and why they sometimes formed with no accident/construction etc. We did some really good science that summer and got stories from it that we can tell to people who aren't at all interested in science - but everyone cares about traffic....)