# Geometric similarity

## Homework Statement

in this question , Lm / Lp = 1/ 6 ? or Lp / Lm = 1/6 ? Lp = length of prototype , Lm = Length of model ## The Attempt at a Solution

i really have no idea... can someone help please?

## Answers and Replies

phinds
Science Advisor
Gold Member
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.

• welovephysics
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 dont 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 ?