Piston Conundrum: Does it Move?

  • Thread starter Thread starter glycerunnin
  • Start date Start date
  • Tags Tags
    Piston
AI Thread Summary
The discussion centers on a piston with equal pressure on both sides, questioning whether it will move. Participants note that if pressure is equal, the piston should not move, as the forces balance out. However, the external pressure on the apparatus could influence the movement, especially since the piston has a shaft extending out. There is also a correction regarding the equation, clarifying that it should be F = PA rather than P = F*A. The overall consensus is that without additional external pressure differences, the piston is likely to remain stationary.
glycerunnin
Messages
3
Reaction score
0

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:
Physics news on Phys.org
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:
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top