Only the best-physics(unit analysis) question

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Homework Help Overview

The problem involves unit analysis related to the radius of a fireball resulting from a bomb, expressed in terms of time, density, and energy. The original poster seeks to verify the relationship between the radius and time through logarithmic plotting.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to understand the requirements of the problem, particularly the significance of plotting log(R) vs log(t) and the meaning of the slope from the fit. Some participants question the clarity of the problem statement and the appropriateness of their attempts at graphing.

Discussion Status

Participants are actively engaging with the problem, with some providing insights into the mathematical relationships involved. There is a recognition of the need for clarification on the plotting method and the interpretation of results, but no consensus has been reached on the approach to take.

Contextual Notes

There is mention of specific time and radius values provided in the problem, which are essential for the analysis. The original poster expresses uncertainty about the vagueness of the question and the implications of the logarithmic transformation.

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Only the best--physics(unit analysis) question

Homework Statement


Ok, this is under the unit analysis section:

-----------> We can express the radius of the fireball (resulting from a bomb) R in terms of t, ρ and E as R= const2x E^(1/x)t^(-y/x)ρ^(−z/x).
Verify the relationship between R and t (That is R is proportional to t^(–y/x)) by plotting log (R) vs log (t) using the information provided in the pictures.
Fit the data of log (R) vs log (t) with a straight line. What is the slope of the
fit? What does the slope mean? Can you see why we are plotting log (R) vs
log (t) instead of R vs t?

--Basically, the pictures show the fireballs of a bomb with the diameter(m) at certain times(ms):
6ms--80m
120ms--110m
53ms--180m


Homework Equations


- Is it me, or is the question too vague? I am trying to understand what it's asking and how I should answer.


The Attempt at a Solution



In the previous question, I have found z= 1 y= -2 and x= 5 for the values in the R=... equation.

However, I don't know what they mean by plotting the log and fitting the data. I have tried graphing log (x) and log (x^(2/5)) but it doens't seem correct.

Thank you in advance.
 
Last edited:
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please anyone??
 
The times correct, particularly the second time.

6ms--80m
120ms--110m
53ms--180m

Normally when one has a function y = exp (kt), one can plot with semi-log, and the slope is the constant k.

if one has R = A tn, then ln R = ln A + n ln t
 

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