Assistance: Large uncertainties making it difficult to plot slopes

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Homework Help Overview

The discussion revolves around plotting data with significant uncertainties, specifically in the context of a practical report involving the cosine of an angle versus temperature. Participants are exploring the implications of these uncertainties on slope calculations and data interpretation.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants inquire about the nature of the plots and the estimation of uncertainties. Questions are raised regarding the maximum temperature of boiling water and its consistency with altitude effects. There is also a discussion about the independence of uncertainties and their impact on slope determination.

Discussion Status

The conversation is ongoing, with participants seeking clarification on various aspects of the problem. Some guidance has been offered regarding the consideration of uncertainties, but no consensus has been reached on the specific issues raised.

Contextual Notes

The original poster mentions high equipment uncertainty affecting their analysis, and there is a reference to altitude-related boiling point discrepancies that may influence the discussion.

Physicist_2
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Homework Statement
This isn't a textbook problem, but rather I am currently writing my practical report and have encountered several problems due to a high equipment uncertainty which has led me to a standstill. Attached is a diagram of my graph with the appropriate uncertainties, however, I am finding it difficult to draw the max and min slopes which encompass all the uncertainty. I would appreciate any guidance. Thank you
Relevant Equations
Thank you
Screen Shot 2019-07-17 at 8.21.24 pm.png
 
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Can you explain a bit more in detail what you are plotting and how you estimated your uncertainties? If you are plotting the cosine of an angle vs. temperature, the point at, say 335 K shows an uncertainty from -0.5 to 1.0 in the cosine which corresponds to an angle uncertainty from 0 to 120 degrees. Is that consistent with what you observed?
 
And how can the max temperature of your boiling water be 360K (~ 87C)? I must be misunderstanding this...
 
berkeman said:
And how can the max temperature of your boiling water be 360K (~ 87C)? I must be misunderstanding this...
According to Wikipedia at an altitude of 12,000 ft water boils at 87.6 ##^o \rm{C}##.
:oldsmile:
 
kuruman said:
According to Wikipedia at an altitude of 12,000 ft water boils at 87.6 ##^o \rm{C}##.
:oldsmile:
Hmm, I used my Mentor superpowers just now to check the OP's location, and unless he went on a road trip to conduct this experiment, he was right around 2000 feet in altitude...

:smile:
 
  • Informative
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Physicist_2 said:
Problem Statement: This isn't a textbook problem, but rather I am currently writing my practical report and have encountered several problems due to a high equipment uncertainty which has led me to a standstill. Attached is a diagram of my graph with the appropriate uncertainties, however, I am finding it difficult to draw the max and min slopes which encompass all the uncertainty. I would appreciate any guidance. Thank you
Relevant Equations: Thank you

View attachment 246749
Further to @kuruman 's comments in post #2, consider whether the uncertainties are independent. Quite possibly there is a source of uncertainty which would have a roughly constant affect across all datapoints, so would not affect the slope much.
 

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