At what time was the yeast added?

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In summary, the conversation is about a story in a Physics book where a girl is murdered by a criminal who adds a special strain of yeast to the bread she was making. The bread starts to rise rapidly, filling the room and killing the girl. The question is at what time the yeast was added. The conversation then discusses different methods of solving the problem, including using a geometric series and logarithms. The final answer is that the yeast was added at 3:48.
  • #1
mborn
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Hi, I had this story in my Physics book

The police was baffled by what seemed to be the prefect nurder of a girlwho had been found, apparently suffocated, in her kitchen. The girl had been making bread in her kitchen, whose dimensions were 6,10, 10 m. she had formed the dough into a ball of volume 1/6 cubic m and turned away to wash some dishes. The criminal added a special virulent strain of yeast to the bread. As a result the bread immediately started to rise in volume, triple every 4 min. before long the dough filled the room, stopping the clock at 3:48 and squashing the girl into the wall. By the time the police came the next day, the yeast worked itself and the dough returned to its normal size.

at what time was the yeast added?

My answer is 3:20 is it true?

M B
 
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  • #2
I got 3:18. Maybe we rounded differently?
 
  • #3
I too (like tide) get t ~ 29 min 50 sec
 
  • #4
Ok!,
Since the answer is not there in my book, I say I solved it as a geometric series, am I right?
 
  • #5
I am not sure what you mean when you say you "solved it as a geometric series." Please explain. :-)
 
  • #6
Well,
a geometric series goes like this
a, ar, a(r^2), a(r^3), ...
General term take the following look
ar^(n-1)
now we have the initial volume (1/6 cubic meter) which is the first term, a.
the nth term is the final volume 6*10*10. therefore we need to know how mnay terms are there to reach 600 starting with 1/6
accordingly;
600=(1/6) * 3^(n-1) and solve for n-1
the time taken to reach the volume 600 is (n-1) * 4 min
since it was found that the clock stopped at 3:48
therefore, t0=3:48 - (n-1)*4

M B
 
  • #7
The question reduces to how you solved that last equation for n. I think it might be clearer if you set up the problem as follows:

Since the volume triples every four minutes you can write the volume as

[tex]V = V_0 \times 3^{t/4}[/tex]

where t is the elapsed time. You can solve for t using logarithms:

[tex]t = 4 \frac {\ln V/V_0}{\ln 3}[/tex]
 
  • #8
same as my answer without rounding.

Thanks

M B
 

1. What is the purpose of adding yeast at a specific time?

Adding yeast at a specific time allows for optimal fermentation, resulting in the desired texture, flavor, and rise of the final product.

2. How will the timing of adding yeast affect my bread or baked goods?

The timing of adding yeast can greatly impact the final product. Adding it too early can result in over-fermentation and a flat, dense product, while adding it too late can lead to under-fermentation and a dense, unrisen product.

3. Can I add yeast at any time during the baking process?

In most cases, it is recommended to add yeast at the beginning of the mixing process. However, some recipes may call for delayed or multiple yeast additions depending on the desired outcome.

4. How do I know when to add yeast?

The recipe or instructions for your specific baked good should indicate when to add the yeast. It is important to follow these guidelines for the best results.

5. Can I add too much yeast if I add it too early?

Yes, adding too much yeast can result in over-fermentation and an undesirable taste. It is important to follow the recommended amount and timing of yeast in your recipe.

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