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Hereformore
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I'm having some trouble reconciling different concepts when it comes to pressure.
I know that:
1) Pressure in a container or in any fluid in a closed container depends on depth by P=Patm + pgd.
2) Pressure is felt on all sides of an object.
So if you have a cube in tank of water, then the cube should feel pressure on all of its sides.
The forces and pressure on the non -top and bottom sides should cancel out because they are equal and opposite each other.
The forces on the top and bottom of the cube, however, do not cancel out because they are at different heights.
The top of the cube should feel a lower pressure than the bottom of the cube, right?
The difference in pressure will equal the difference in depth so: Pbottom-Ptop = pg(Depth at Bottom - Depth at Top of Cube).
So if you have a cube that is submeged in water as shown above, and if it is not moving up or down (so its still, all forces cancel), we have the forces:
Fy = Fw - Fbouyancy = 0 N
For Pressure we have: P Bottom > Ptop from the water. What other component am I missing? If the pressure from the bottom is larger than the pressure pushing down from the top, then the object should be moving up shouldn't it? Or am I misunderstanding pressure at different depths completely.
This leads to my followup question: we know pressure at lower depths is greater, but that means that at lower depths you feel a greater force and pressure. But intuitively you would think that at lower depths the pressure would be greater downards weighing down upon you wouldn't you?
But for floating objects, although the presure is greater, it points up?
Edit: Oh wait! Is it actually kind of like the water is pushing back up against the bottom of the cube? Or is it something else entirely? I can't wrap my head around the greater pressure at a lower depth pointing opposite the very mass/liquid that gives it its greater pressure.
I know that:
1) Pressure in a container or in any fluid in a closed container depends on depth by P=Patm + pgd.
2) Pressure is felt on all sides of an object.
So if you have a cube in tank of water, then the cube should feel pressure on all of its sides.
The forces and pressure on the non -top and bottom sides should cancel out because they are equal and opposite each other.
The forces on the top and bottom of the cube, however, do not cancel out because they are at different heights.
The top of the cube should feel a lower pressure than the bottom of the cube, right?
The difference in pressure will equal the difference in depth so: Pbottom-Ptop = pg(Depth at Bottom - Depth at Top of Cube).
So if you have a cube that is submeged in water as shown above, and if it is not moving up or down (so its still, all forces cancel), we have the forces:
Fy = Fw - Fbouyancy = 0 N
For Pressure we have: P Bottom > Ptop from the water. What other component am I missing? If the pressure from the bottom is larger than the pressure pushing down from the top, then the object should be moving up shouldn't it? Or am I misunderstanding pressure at different depths completely.
This leads to my followup question: we know pressure at lower depths is greater, but that means that at lower depths you feel a greater force and pressure. But intuitively you would think that at lower depths the pressure would be greater downards weighing down upon you wouldn't you?
But for floating objects, although the presure is greater, it points up?
Edit: Oh wait! Is it actually kind of like the water is pushing back up against the bottom of the cube? Or is it something else entirely? I can't wrap my head around the greater pressure at a lower depth pointing opposite the very mass/liquid that gives it its greater pressure.
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