Pressure question
Thread Starter
Joined: Aug 2005
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From: Durham, United Kingdom
Pressure question
I was asked this question and i dont know the answer so if anyone could help me it would be great,
say you have a cuboid length being 3cm height and breadth being 2 cm and inside the cuboid the atmosphere is 3x's its norm, is there a greater amount of force acting on the 4cm(squared) side then the 6cm(squared) side
i know that Pressure = Force/Area therefore Force = Pressure X Area
Any help
say you have a cuboid length being 3cm height and breadth being 2 cm and inside the cuboid the atmosphere is 3x's its norm, is there a greater amount of force acting on the 4cm(squared) side then the 6cm(squared) side
i know that Pressure = Force/Area therefore Force = Pressure X Area
Any help
Combine Operations
Joined: May 2005
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From: U.K.
Re: Pressure question
Originally Posted by DrRedHead
i know that Pressure = Force/Area therefore Force = Pressure X Area
Any help
Any help
Pressure is constant throughout, so each square unit has the same force acting on it. So, double the area, for instance, and you double the force.
Joined: Aug 2005
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From: Estonia
Re: Pressure question
Indeed. And the answer is true.
That has been called "hydraulic paradox". Applying a small amount of force on a small surface can bring about a larger force on a larger surface, because the pressure in a closed vessel of fluid is uniform (neglecting gravity etc.).
Note that if you actually move the surfaces, then the pressure inside stays constant if the volume stays constant. Which it does if the volume changes on both surfaces cancel out. And they do, if the smaller surface moves for a larger distance than the larger surface.
Effectively, a fluid can amplify forces exactly as levers do - large movement of a small force can cause small movement of a large force.
And the 4 cm squared side will, of course, have a smaller force acting on it than the 6 cm squared side.
That has been called "hydraulic paradox". Applying a small amount of force on a small surface can bring about a larger force on a larger surface, because the pressure in a closed vessel of fluid is uniform (neglecting gravity etc.).
Note that if you actually move the surfaces, then the pressure inside stays constant if the volume stays constant. Which it does if the volume changes on both surfaces cancel out. And they do, if the smaller surface moves for a larger distance than the larger surface.
Effectively, a fluid can amplify forces exactly as levers do - large movement of a small force can cause small movement of a large force.
And the 4 cm squared side will, of course, have a smaller force acting on it than the 6 cm squared side.
