Piston Conundrum: Does it Move?

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Homework Help Overview

The discussion revolves around a piston system where the pressure on either side of the piston is stated to be equivalent. The original poster questions the movement of the piston under these conditions, exploring the implications of pressure and force on both sides.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to analyze the situation by considering the effects of pressure and volume changes on the piston. They express uncertainty about the piston’s movement given equal pressures. Other participants question the setup, particularly regarding external pressures and the presence of a stopper in the tube.

Discussion Status

The discussion is ongoing, with participants exploring different aspects of the problem. Some guidance has been offered regarding the importance of external pressures, but no consensus has been reached on the piston’s movement.

Contextual Notes

There is mention of a potential stopper in the tube, which may influence the system's behavior. The original poster also reflects on their understanding of the relationship between pressure, force, and area, indicating a need for clarification on these concepts.

glycerunnin
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Homework Statement



In the picture below, the pressure on either side of the piston is equivalent. The question asks which direction the piston moves (or if it even moves at all).

http://imageshack.us/a/img203/1830/photoon3613at919pm.jpg

Homework Equations



P1*V1 = P2*V2 = C

P = F*A

The Attempt at a Solution



Moving the piston to the left decreases volume in the cylinder, and moving the piston to the right increases the volume in the cylinder, but I see no reason for the piston to move if the pressure on both sides is equal. Also, the force on the right side of the piston is less than that on the left side, making the force greater on the right side if we use the equation P = F*A and pressure is equal on both sides. At first glance it just looks like it will not move, but I feel like I am underthinking it.
 
Last edited by a moderator:
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What is that in the left end of the tube?

ehild
 
ehild said:
What is that in the left end of the tube?

ehild

Probably a stopper.
 
glycerunnin said:
Also, the force on the right side of the piston is less than that on the left side, [...]
Well, that depends. What is the pressure on the outside of the entire apparatus? More specifically, how does the pressure on the outside of the apparatus compare to the pressure inside? That plays a role, given that the shaft is sticking out.

---------------------------
Edit:

Oh, and by the way,
[...] the equation P = F*A [...]
I think you mean F = PA.
 
Last edited:

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