Geometric Similarity: Solving for Lp and Lm | Prototype and Model Lengths

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Homework Help Overview

The discussion revolves around geometric similarity in the context of prototype and model lengths, specifically focusing on the ratio of lengths (Lp and Lm) and their implications in fluid dynamics. Participants are trying to clarify the relationships between these lengths and the associated equations.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants are questioning the correct ratio of Lm to Lp and whether it should be 1/6 or the inverse. There are attempts to derive relationships using kinematic viscosity and velocity ratios, with some participants expressing uncertainty about their reasoning.

Discussion Status

The discussion is ongoing, with participants providing different interpretations of the problem. Some have suggested potential relationships and equations, while others are seeking clarification on the initial setup and the assumptions involved.

Contextual Notes

There is a mention of the participant's educational level and the source of the problem, indicating that the context may influence the understanding of the concepts being discussed. The need for more background information to provide meaningful assistance has also been highlighted.

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Homework Statement



in this question , Lm / Lp = 1/ 6 ? or Lp / Lm = 1/6 ? Lp = length of prototype , Lm = Length of model

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Homework Equations

The Attempt at a Solution


i really have no idea... can someone help please?
 
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If you have no idea at all then the question arises, how do you come to be working on a problem that you have no idea how to answer? What level of school are you in? Where is the problem from? We don't spoon-feed answers here, we try to help you solve a problem yourself, but we need more background to even be able to give you a hint that would be meaningful to you.
 
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phinds said:
If you have no idea at all then the question arises, how do you come to be working on a problem that you have no idea how to answer? What level of school are you in? Where is the problem from? We don't spoon-feed answers here, we try to help you solve a problem yourself, but we need more background to even be able to give you a hint that would be meaningful to you.
i am in uni now , and the notes is from my book , IMO , it should be Lp / Lm = 1/6 , am i right ?
can you help ?
 
i don't think the working provided is correct
IMO , it should be (Vr)( Lr )= (nu)r

nu = kinematic viscosity
since nu is constant , so ,

Vp / Vm = Lm / Lp
60 / Vm = 1/6

so , Vm = 360km/h , am i right ?

thus , force has formula of ρ(L^3)(velocity) , so force is directly proportional to v ,

Fp / Fm = Vp / Vm
Fp / 250 = 60/360 , Fp = 41.7N , is it correct ?
 

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