Work to pump out air from cylinder

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Homework Help Overview

The discussion revolves around calculating the work required to pump air out of a cylindrical air tank, given only its length and cross-sectional area. Participants are exploring the implications of using pressure in their calculations, particularly in the context of undefined initial pressure.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants are considering the formula W = pV for calculating work and questioning the appropriateness of using atmospheric pressure as the initial pressure due to its undefined nature in the problem statement.

Discussion Status

The discussion is ongoing, with participants clarifying the context of the cylinder and exploring different interpretations of the problem. There is no explicit consensus yet, but some guidance on the formula and its variables has been provided.

Contextual Notes

The initial pressure is not defined in the problem, leading to questions about whether atmospheric pressure can be used in calculations. This uncertainty may affect the approach to the problem.

Stefan

Homework Statement


[/B]
I know only the length (l) and cross-section area (S) of an air tank, cylinder. The question is how much work is needed to pump out air from the cylinder.

Homework Equations

The Attempt at a Solution


Is it correct to use here the formula
W = pV?
The initial pressure isn't defined in the content of the task, so I am also wondering if I can use as it the atmospheric pressure.
 
Last edited by a moderator:
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What do you mean by cylinder ?

An air tank or the working cylinder of an air pump ?
 
Air tank.
 
Stefan said:

Homework Statement


I know only the length (l) and cross-section area (S) of an air tank, cylinder. The question is how much work is needed to pump out air from the cylinder.

Homework Equations


3. The Attempt at a Solution [/B]
Is it correct to use here the formula
W = pV?
The initial pressure isn't defined in the content of the task, so I am also wondering if I can use as it the atmospheric pressure.
There may be more than one answer to this question, but the method I have in mind would definitely agree with your answer: Work = pV, V = Sl, p = 1 at.
 

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