Mistake in Dynamics Circular Problem's Solution

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Homework Help Overview

The discussion revolves around a dynamics problem involving circular motion, specifically focusing on the calculation of radius and tension in a string. Participants are examining discrepancies in the reported solutions and their own calculations.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants are comparing their calculated radius with the provided solution, questioning the accuracy of significant figures in their computations. There is an exploration of how rounding affects the results, particularly in the context of tension calculations.

Discussion Status

The discussion is active, with participants providing guidance on maintaining significant figures and clarifying the implications of these figures on their results. There is acknowledgment of potential errors in the original problem's reported values, but no consensus has been reached regarding the final answers.

Contextual Notes

Participants note that the problem's numbers are stated to three significant figures, which is influencing their calculations and discussions about accuracy. There is also mention of a possible typographical error in the reported radius value.

alingy1
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Please look at pictures.
I do not understand the solutions;

Here is how I find length of string:
5m/s*1.2s/rev=6m/rev=circumference=2piR
R=0.95m.


For the force:
T=mv^2/r= 0.350 kg *5^2/0.95= 9.21N They got 9.16N?
 

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The numbers in the problem are stated to 3 significant figures. So, make sure you keep at least 3 significant figures in your intermediate calculations. What do you get for R to 3 significant figures?
 
Well the answer I got is 0.95m which is almost twice as big as the radius they found.
I keep all my sig figs on my calculator.
 
I don't know what is going on! :O
 
You got R = .95 m. That has only 2 significant figures. What do you get to 3 significant figures?

When you calculated T, it looks like you used r = .95 m. Again, only 2 significant figures for r. What do you get for T if you use a value for r that is accurate to 3 significant figures?
 
OK, I did not see the answer they had for R. Their answer is wrong, yours is right. But you should give it to 3 significant figures.
 
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R=0.955m.
T=9.16N. You were right! Ok. This was my bad.
What about the radius? The radius they report is definitely wrong?
 
Perfect! Everything works out great!
 
Good!
 
  • #10
their radius is mistyped- probably 4 was meant to be a 9...
as for the rest, follow TSny's post
 

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