# Homework Help: Rate of evaporation physics help

1. May 14, 2006

### Srinand

I am in my first year of the IB Diploma and I have chosen Higher Physics and want to do my extended essay in Physics. Is fluid dynamics (or fluid mechanics i.e. how things fall in water and why) better or is analyzing the effect of colors on the rate of evaporation better? This essay has to be in the realms of practical physics (i.e. no dark energy and anti-matter sort of topics). Which is a better choice?

2. May 14, 2006

### Gokul43201

Staff Emeritus
Very few people here know what an IB Diploma is, so if that is important information (and I think it is), you should explain it.

As for your two choices, the first is extremely broad and the second is much narrower (and also very unclear). Which is better ? That depends on what you want it to be better for. What are your criteria for a better topic ?

In any case, you need to clarify what you mean by the second topic. The color of what ? The evaporation of what ?

3. May 15, 2006

### Srinand

The IB Diploma is a substitute for the A level system. In the first choice (fluid dynamics) I would like to research on how things fall in water, does their mass have any other effect than making it drop faster? How much of a factor is drag? And try to find an equation to things dropping in water. As for the second one, the title is whether colors in the EM spectrum a.k.a visible light (i.e ROYGBIV) in the form of opaque ink, when added to water, make a different to the rate of evaporation. And also, in the second question, I was thinking of analyzing whether colours can absorb infrared radiation and which colours (if they do) absorb the most. And also, my theory for the second question is that since sunlight is yellow, yellow ink dissolved in water should be the hottest solution. Here is a passage from the range and suitability of the work from an IB Physics Extended Essay guide:

Investigations covered several domains of Physics including mechanics, the most popular (i.e. effiecieny of a dynam, wind energy, airplane models in wind tunnels etc.), sound, electricity, thermodynamics, optics, atomic and nuclear physics and astrophysics. Other 'exotic' topics included nanotechnology, time travel, space engines, plasma physics, superluminal velocity and photon enlargenment. These last topics were either too new or too difficult to be dealt with efficiently within an extended essay (which has a 4000 word limit). The best essays were generally involving an experimental investigation performed by the candidate or, to a lesser extent, databased topics. Some essays were far too simplistic an investigation. A number of essays were original, imaginative and highly focused. However, a number of topics were too broad and generated only a very superficial survey."

Hope that extract helped. We are assesed on the following Criterion:

Criterion A: Research Question
Criterion B: Approach to Research Question
Criterion C: Analysis/ Interpretation
Criterion D: Argument/ Evaluation
Criterion E: Principles of Physics
Criterion D: Reasoning surrounding the research and its limitations

PLEASE EVERYBODY HELP ME OUT HERE! THIS IS A VERY IMPORTANT THING! IF THERE ARE ANY TEACHERS ON THIS BOARD OR DIPLOMA HOLDERS, YOUR INPUT IS LIKE GOLD!!!

4. May 15, 2006

### chroot

Staff Emeritus
I received an IB diploma way back in 1997. My extended essay was essentially a rehash of a science fair project I did a year earlier (which won a 2nd place grand award at the International Science and Engineering Fair that year). That particular project involved using neural networks to analyze natural language (i.e. english), in an effort to figure out what it means to "know" a word. My thesis was that words are meaningful only in their relationship to other words, and a dumb computer system could emulate human understanding of language -- even the nuances and secondary definitions of words -- with nothing more than a basic neural network.

Personally, I think your project involving the rate of evaporation is far too simplistic for an IB extended essay. Really, a school child could conceive and perform the same experiment in a few days. By the way, your theory about yellow pigment is wrong; the pigment that absorbs the most radiation, of all wavelengths, is obviously black.

If you wanted to study colors or pigments and their interaction with light, I strongly suggest you deepen your investigation. Find (or build) a spectrophotometer, and analyze the absorption spectra of the pigments. Use additional photoreactive chemicals to try to tailor a pigment to have some desired absorption spectra. Think of the many uses a custom pigment might have in industrial applications, and work on developing a pigment . Develop a pigment that passes visible light, but blocks most of the infrared and ultraviolet, and explain how it could used as a next-generation window treatment.

That's the sort of investigation the IB committee wants to see. They want you to find a problem, then address the problem with research, indepedent thought, and experimentation. They don't want to see a grade-school science fair project you wrote up in two evenings.

- Warren

5. May 16, 2006