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I'm a high school student and we have to research a topic in physics as part of our school curriculum. Essentially, I am unable to find any text online relating to this topic, so I was wondering if the topic was worth pursuing. Taking a constant temperature and volume of various liquids/semi-solids such as water, honey, glue, etc, I will drop an object of constant mass into it. I would like to derive a relationship between say the density or another similar property of the fluid and its ability to reduce the force applied, say for example, honey does a better job of dispersing the force applied than water does? Is there a field for this kind of study? I am unable to find much online, only a few links relating to the shock absorption properties of some industry materials.

Additionally, I am confused as to what equipment is required. When the shock absorption capabilities of a solid are tested, how do they measure how this force is dispersed? I was thinking of force sensitive resistors for the Raspberry pi placed right below the surface, but I am unsure whether or not this method would give me the final force at the point of impact, after having been dampened by the fluid. Thanks!

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  • $\begingroup$ Hi, welcome to Physics SE! The question "is this feasible?" is generally not encouraged, as it's difficult for any of us to know how advanced your knowledge. This is necessary if we're to answer that. And anyways, the answer is just yes/no, which isn't suitable for a Q&A site. Can you rephrase your question to just focus on the methods of measuring the force applied on the surface of a fluid? Also, it would be helpful if you could describe your current idea with some more details... $\endgroup$ – user191954 May 24 '18 at 13:33
  • $\begingroup$ Alternatively, you could consider asking a separate question about the topic which will introduce you to the mathematical rigor and theoretical complexity of the topic. Then you'll be able to judge the difficulty on your own. $\endgroup$ – user191954 May 24 '18 at 13:34
  • $\begingroup$ Thanks for the reply. Essentially, I am unable to find any text online relating to this topic, so I was wondering if the topic was worth pursuing. Taking a constant temperature and volume of various liquids/semi-solids such as water, honey, glue, etc, I will drop an object of constant mass into it. I would like to derive a relationship between say the density or another similar property of the fluid and its ability to reduce the force applied, say for example, honey does a better job of dispersing the force applied than water does. $\endgroup$ – Zombaka May 24 '18 at 13:44
  • $\begingroup$ That's useful information. Try including that in your question, and decreasing the emphasis on your background and the feasibility. Ask for the theory behind the concepts. $\endgroup$ – user191954 May 24 '18 at 13:46
  • $\begingroup$ What confuses me is how to measure this value. If I were to place a force sensitive resistor right below the surface of each fluid, would I get the same value since based on F=ma, the force exerted on the surface is the same regardless? Furthermore, I do not know how shock absorption or forces are measured at an industrial level, is there some specialised equipment that is required, and hence I can not measure it using these resistors? $\endgroup$ – Zombaka May 24 '18 at 13:47
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I think that you first need to consider what is the quantity you are interested in and then decide what is the best way to measure this quantity. One thing you mention is the force applied, but on what? The bottom of your container, the object you place in the fluid?

Without giving away all the answers, I think that you should do some research on buoyancy force as you will find that it is related to the density of the fluid. Another, slightly more challenging project would be to look at viscosity, in which case you should research falling sphere viscometers. For both of these projects, you should be able to design and execute relatively simple experiments.

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Congratulations on picking an active and important area of research: water entry of projectiles. You will need someone from a university to help you understand it.

To measure the impact on the solid upon entry into a liquid, you can simply record the solid body's trajectory, i.e. its position vs time information. If you use high-speed camera to record its position over time, you can then calculate its velocity and acceleration, calculate its loss of momentum upon entry, etc. This much might be good enough for a high-school project.

(try this if the link in the beginning doesn't work: https://s3.amazonaws.com/academia.edu.documents/46114158/Water_Entry_of_Projectiles20160531-7907-1p6he9b.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1527401594&Signature=q%2FvJ0Xuz9Wk8DAqkcmCPb9tV6hU%3D&response-content-disposition=inline%3B%20filename%3DWater_Entry_of_Projectiles.pdf)

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  • $\begingroup$ Your link is broken. $\endgroup$ – sammy gerbil May 25 '18 at 22:35
  • $\begingroup$ @sammygerbil Sorry. Corrected. $\endgroup$ – Deep May 26 '18 at 4:52

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