Solve Dimensional Analysis: Find Dimensions of B

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Homework Help Overview

The problem involves finding the dimensions of variable B in the equation A = B^3C^(1/2), where A has dimensions of L/M and C has dimensions of L/T. Participants are exploring dimensional analysis to determine B's dimensions.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss substituting dimensions into the equation to match the left-hand side with the right-hand side. There are attempts to manipulate the equation to isolate B, with some questioning the clarity of their steps and the need for proper grouping of terms.

Discussion Status

The discussion is ongoing, with participants providing various approaches to isolate B's dimensions. Some have pointed out potential errors in arithmetic and the need for clearer notation, while others are still trying to reconcile their results with the original equation.

Contextual Notes

There are indications of confusion regarding the manipulation of dimensions and the proper use of parentheses for clarity. Participants are also addressing the implications of squaring terms in their calculations.

Pajamas
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Homework Statement


A=B^3C^1/2 where A has the dimensions L/M and C has dimensions L/T. What are the dimensions of B?


Homework Equations




The Attempt at a Solution


When I worked the problem I got B=M/T but it is wrong. I'm not sure how to approach the question.
 
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You substitute the dimensions into the equation and work out what dimenstions B has to have to make the LHS match the RHS.

Please show your working.
 
So far I have B^3=TL/M^2

L/M=B^3(L/T)^1/2
with L/T then in the square root, square both sides and get T/L*L/M^2=B^3, cancel the L on bottom and one on top to get the above answer.
 
This doesn't make a lot of sense to me since B is still B^3. Am I supposed to have it look similar to the other side with TLM?
 
Pajamas said:
So far I have B^3=TL/M^2

L/M=B^3(L/T)^1/2
with L/T then in the square root, square both sides and get T/L*L/M^2=B^3, cancel the L on bottom and one on top to get the above answer.

You have several errors in this.
Squaring will produce B^6. And L^2 in L/M.
Using parentheses will make the things clearer. For you as well as for the people reading your posts.
You don't need to square. Just solve for B and put the dimensions.
 
T/L*L/M^2=T/L^2/M^2=T/(L^2M^2) ...

Yike... you need to use brackets more to group your terms.
Use square brackets to represent when you mean "dimensions of"[B^3]=(T/L)(L/M^2)=T/(M^2)

OK - but you need ... you've not finished.
(And - check your arithmetic.)
 
Last edited:

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