What Happens When a Piston is Added to a Cylinder in Pascal's Law Experiment?

In summary, the question is about the effect of adding a piston inside one of the cylinders in a classic drawing of Pascal's law. The conversation discusses two hypotheses, but the correct answer is that the piston will move until the pressures on both sides are equal. The liquid in column A will move downward and the piston will move upward until equilibrium is reached.
  • #1
Baxidur
8
0
Hi

First off I'm not a student, this is purely a curiosity question

In pascals law classic drawing if you added a piston inside one of the cylinders what would happen?

I've added a drawing to clarify

I'm totally split on what the answer is, Pascals law seems to state the pressure on both sides of the piston will be equal, but real life seems to say the weight of the water in B will push the piston down

Thanks in advance for any help
 

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  • #2
Hi Baxidur! :smile:
Baxidur said:
… real life seems to say the weight of the water in B will push the piston down

is the weight of the water in B pushing anything else down? :wink:
 
  • #3
Not that I can see
 
  • #4
What about the bottom of the tank (on either side of the downpipe)? :wink:
 
  • #5
Baxidur said:
Hi

First off I'm not a student, this is purely a curiosity question

In pascals law classic drawing if you added a piston inside one of the cylinders what would happen?

I've added a drawing to clarify

I'm totally split on what the answer is, Pascals law seems to state the pressure on both sides of the piston will be equal, but real life seems to say the weight of the water in B will push the piston down

Thanks in advance for any help

Neither of your hypotheses is correct. The piston will not move downward, and the piston will not stay stationary. There is a third choice, and this is the correct answer.

The upward pressure on the bottom of the piston is initially higher than the downward pressure on the top of the piston. Since the piston has no weight (and there is no friction), there will be a net force on it. The liquid in column A will move downward (and the piston will move upward) until the pressures on the top and bottom of the piston are equilibrated.

Chet
 

Related to What Happens When a Piston is Added to a Cylinder in Pascal's Law Experiment?

1. What is static fluid mechanics?

Static fluid mechanics is a branch of fluid mechanics that deals with fluids at rest, also known as static fluids. It involves the study of the behavior and properties of fluids that are not in motion. This can include the analysis of pressure, density, and forces acting on a fluid at rest.

2. How is pressure defined in static fluid mechanics?

In static fluid mechanics, pressure is defined as the force per unit area exerted by a fluid on its surroundings. It is a scalar quantity and is typically measured in units of Pascals (Pa) or pounds per square inch (psi). Pressure in a fluid is caused by the weight of the fluid above it and is transmitted equally in all directions.

3. What is the difference between hydrostatics and hydrodynamics?

Hydrostatics is a subfield of static fluid mechanics that deals with the behavior of fluids at rest, while hydrodynamics deals with the study of fluids in motion. Hydrostatics focuses on the forces and pressures acting on a fluid at rest, while hydrodynamics also considers the effects of fluid flow and viscosity.

4. How does Archimedes' principle relate to static fluid mechanics?

Archimedes' principle states that the buoyant force on an object submerged in a fluid is equal to the weight of the displaced fluid. In static fluid mechanics, this principle is used to calculate the buoyant force acting on an object in a fluid, which can help determine whether the object will float or sink.

5. What are some practical applications of static fluid mechanics?

Static fluid mechanics has many practical applications, including the design and construction of buildings, bridges, and dams. It is also used in the design of hydraulic systems, such as pumps and turbines, and in the study of weather patterns and ocean currents. In addition, static fluid mechanics is important in the fields of aeronautics and aerospace engineering, as it helps to understand the behavior of fluids in aircraft and spacecraft.

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