IBDP Extended Essay Ideas -- Help please

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Homework Statement

Don't know what to do for ibdp extended essay topic

Relevant Equations

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Hey, I'm a first year IB student (G11) starting my extended essay. It's a 4000 word essay where you explore something outside the IB syllabus, and basically write a research project on it. I'm struggling thinking of a topic for my research question.

Right now I've got the research question "How does the size of a gas bubble affect its rise velocity in a fluid with varying viscosity?" where I use newtonian fluids (water) and non newtonian fluids (syrup or honey) to investigate the speed of different sized bubble rising. But the problem for this RQ is that I don't know how to control the size of the bubbles (syringe? blow with straw?) as school equipment are limited.

And another problem is that for the extended essay it's better to have a equation or constant you verify and I don't have that either. My second idea was something on special relativity, as I really liked time dilation and I just think it's so cool!!! So for this one I was thinking of creating a simulation of the "light clock" with a laser pointer, instructions shown below.

"Light Clock" Simulation with a Laser Pointer​

• What It Shows: The fundamental principle behind time dilation using a light clock analogy.
• How to Simulate:
  • Create a "light clock" by bouncing a laser pointer off two mirrors.
  • Move the mirrors horizontally while shining the laser.
  • Record the apparent change in the light's path due to motion and discuss how this models relativistic time dilation.
• Materials: Laser pointer, mirrors, ruler, and stopwatch.

What do you guys think? Thanks!!

 

[kuruman]

My general advice for students who are facing experimental projects such as yours is "Don't bite off more than you can chew." On one hand the project must be something that interests you otherwise the result might be a half-hearted crappy job that will leave you unsatisfied. On the other hand it must be something that you can do, with what you know, where you are in the time that you have. Only you can gauge that, therefore you need to do some planning before that. If you see experimental limitations, try to be inventive and overcome them. If you lack an equation to verify, do some research and see if it exists and if not, try to derive it. If you cannot derive it, plot the dependent variable $y$ vs. the dependent variable $x$ and see if you can deduce the functional dependence $y=f(x)$ from the plot. Then see if you can find an justification for that equation in terms of physical principles that you know and understand.

Of the projects that you have selected, the light clock seems to be unrealistic. You have not explained how you plan to use the stopwatch, but if you plan to start and stop it by hand while light is traveling from A to B, you need to consider that human reaction time is of order of 0.1 s. In that time, light travels 10,000 km. If you plan to use something other than light to simulate, as you say, the light clock not that any simulation with anything other than light traveling between A and B might be inappropriate because only light travels at the same speed in all frames of reference.

But the problem for this RQ is that I don't know how to control the size of the bubbles (syringe? blow with straw?) as school equipment are limited. And another problem is that for the extended essay it's better to have a equation or constant you verify and I don't have that either.

The bubble project seems to be more realistic. If controlling the size of the bubble is a problem, be inventive with what you have. Here is what I would try if I were you. I would use an eyedropper (they are cheap) and calibrate it. This means fill it with water, squeeze out some of the water on the pan of an scale that can measure small masses (your school must own one or two). I would figure out the volume of the water from its mass. I would mark the air-water interface on the eyedropper. I would repeat with the now marked eyedropper to verify that the squozen water indeed has the volume that I think it does. Repeating this many times will give you an estimate of the experimental uncertainty in the size of the bubble. For a different volume, I would not get greedy and try to put more marks on the eyedropper. I would use a second eyedropper. Like I said, be inventive.

 

[berkeman]

squozen water

And today I learned a new word!