Simplistic wrote:I would like to do a project in Enginneering because i want to become an Enginneer. However, every project relating to it is outside my respective field in Enginneering or is a project designed to build something, instead of testing a question, which is the whole purpose of the Science Fair Project.
I found a question, "how much of the gravitational potential energy of a marble at the starting point is converted to the kinetic energy of the marble at various points along the track," and i think its kindof interesting but i would really like to find a project more in relating to mechanical and biomedical enginneering. Is it possible to find one more relating to that field in enginneering or should i just stick to that question. I would really like to do a project i like, but i am still unsure...
Thank you for reading this...

Simplistic,
There are several engineers on this forum and I'm sure they will chime in with suggestions about how to make a great engineering science project, but I thought I would jump in with a few suggestions, since I work in biophysics and some of my coworkers are biomedical engineers. A lot of what they study is what I study... they want to make devices and engineer things, but first they have to understand the basic science.
I would recommend coming up with an device that interests you, and then break it down and see how you can improve it. When you find the weak point, the failure point, you can define a question, and use the scientific method to address the investigation of the solution.
Let me give you an example of how to do this. Devices that are implanted in the human body have to have special characteristics. For example, the body responds to some foreign objects and attacks them. The human body also is an aqueous environment, with lots of ions floating around, so the material has to be resistant to chemical attack. A science project can be testing materials to find which one has the most beneficial properties (resistance to protein adhesion, resistance to corrosion or whatever). The motivation is engineering- but the testing method is the scientific method. Your different materials are the variables, the measured variable is the amount of corrosion or adhesion, etc.
The sciencebuddies website has some interesting biotechnology projects at:
https://www.sciencebuddies.org/mentorin ... ?from=Home
I don't know if any of these interest you.
I think the marble idea may be too simplistic. You don't say what your grade level is, but I'm guessing you are an older student. It could work, but you would need to add an original twist.
Hope this helps!
Louise