Dodgy solution for a thermodynamics problem?

In summary, the conversation discusses the relationship between pressure, temperature, and the amount of gas in a volume. The ideal gas law is used to explain how this relationship changes in scenarios where the temperature is constant and where it increases. The conversation also addresses the question of whether the increase in pressure in the first scenario also causes an increase in temperature. The summary concludes by stating that in the scenario where temperature is increasing, there is less of a change in pressure for the same amount of gas compared to the scenario where temperature is constant.
  • #1
aspodkfpo
148
5
Homework Statement
n/a
Relevant Equations
PV=nrT
https://www.asi.edu.au/wp-content/uploads/2020/07/ASOE_Physics_2019-answers.pdf

Question 14 B) Re: " The graph of force per area vs amount of gas will change, as the pressure is increasing due to increasing temperature, so the amount of gas in a volume at a given pressure will be decreasing. This will have the effect of decreasing the maximum force per area for there to be no gas in the bubble, and also decreasing the rate of increase of force per area beyond that point. "

Cannot understand this, can someone explain this more? Also with their reasoning it seems that they ignore that the pressure rise in the first scenario also causes an increasing temperature?
 
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  • #2
I think what it is trying to say without equations is this.
First, the ideal gas law in 14(b) is written as ##pV=AT## where ##A## is a measure of the amount of gas.
Now for a (nearly) constant volume process, ##d(pV)\approx Vdp##.
The other side of the equation is ##d[AT]=T dA+AdT##.
So ##dp \sim T dA+AdT.##

In 14(a) there is no change in temperature so ##dp \sim T dA.##
In 14(b) there is change in temperature so ##dp \sim T dA +AdT.##
For the same ##dA## there is less ##dp## in 14(b) than in 14(a) point by point.
 

1. What is a dodgy solution for a thermodynamics problem?

A dodgy solution for a thermodynamics problem is a solution that is not accurate or reliable. It may involve shortcuts or assumptions that do not fully consider all relevant factors.

2. Why would someone use a dodgy solution for a thermodynamics problem?

Some people may use a dodgy solution because they are pressed for time or lack the knowledge or resources to find a more accurate solution. Others may use it as a temporary solution until they can find a better one.

3. Are dodgy solutions ever acceptable in scientific research?

No, dodgy solutions are not acceptable in scientific research. They can lead to incorrect conclusions and compromise the integrity of the research.

4. How can you identify a dodgy solution for a thermodynamics problem?

A dodgy solution may involve oversimplifications, unrealistic assumptions, or illogical reasoning. It may also yield results that are significantly different from those obtained through more rigorous methods.

5. What are the potential consequences of using a dodgy solution for a thermodynamics problem?

The consequences of using a dodgy solution can range from minor errors to major miscalculations. Inaccurate solutions can also lead to incorrect predictions and hinder progress in scientific understanding and technological advancements.

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