- #1
beginner16
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hello
Buoyancy is the upward force exerted on an object immersed in fluid, and upward force on an object in a fluid is equal to the weight of the fluid that was displaced.
If this bouyant force is less than the weight of the object itself, the object will be left with a net downward force and will sink. If the object floats, it floats enough that the bouyant force exactly balances its weight.
Object and water pushing on object from above together have force F[Now] (which is weight of an object + weight of a water above object ), so shouldn't the water below object also be pushing back with equal but opposite force, since that is what the 3. Newton's law says?
Afterall, the pressure on water of area A at depth H is caused by the weight
( F[water_above] ) that the water (its volume is A*height) located directly above has. And that is why water at depth H is pushing upwards with force equal but opposite to F[water_above].
So if a part of fluid was displaced with an object it would suggest that now instead of F[water_above] force exerted on water at depth H is
F[Now]=F[water_above] - F[displaced_fluid] + F[object]
So why doesn't water at depth H push back with equal but opposite to the force F[Now]?
Instead it pushes with force equal but opposite to F[water_above], as if the displaced water was still in its place?
thank you
Buoyancy is the upward force exerted on an object immersed in fluid, and upward force on an object in a fluid is equal to the weight of the fluid that was displaced.
If this bouyant force is less than the weight of the object itself, the object will be left with a net downward force and will sink. If the object floats, it floats enough that the bouyant force exactly balances its weight.
Object and water pushing on object from above together have force F[Now] (which is weight of an object + weight of a water above object ), so shouldn't the water below object also be pushing back with equal but opposite force, since that is what the 3. Newton's law says?
Afterall, the pressure on water of area A at depth H is caused by the weight
( F[water_above] ) that the water (its volume is A*height) located directly above has. And that is why water at depth H is pushing upwards with force equal but opposite to F[water_above].
So if a part of fluid was displaced with an object it would suggest that now instead of F[water_above] force exerted on water at depth H is
F[Now]=F[water_above] - F[displaced_fluid] + F[object]
So why doesn't water at depth H push back with equal but opposite to the force F[Now]?
Instead it pushes with force equal but opposite to F[water_above], as if the displaced water was still in its place?
thank you