1)How can a fluid exert pressure in all directions ?The only force that a fluid exerts is its weight (as far as I know) and as weight acts downwards, fluids should only exert pressure in the downward direction. Also why do they say fluids exert pressure in all directions ? Why can't they say fluids exert force in all directions? 2)Why do liquids exert an upward force on objects ? Is it because the object exerts a downward force on the liquid, so the liquid exerts a reaction force on the object ? If that is true then since action = reaction, the upward force should push the object up with a force equal to the objects weight which means that all objects should float. Also,if the reaction force is not the upward force then what happens to the reaction force ? 3)If we push a cork to the bottom of a bucket of water it shoots back up. My textbook says that this is due to the upward force of water on the object, but if that is true then why doesn't water exert a downward force on the object (maybe the downward force could be its weight ?) because water exerts pressure in all directions, including downwards ? 4)In my textbook there is a picture of a guy underwater picking up a treasure chest or something that looks like a treasure chest and under the picture they have written that it weighs less underwater so he can easily pick it up. But how would it be easier to pick it up as it would be lying on the floor so there would be no water underneath it so how could could the water exert an upward force on it ? Is it through the irregularities on its surface ? If yes, then what if it was a perfectly smooth box? EDIT: After doing a bit of research on the internet I think I understand a bit ( but I'd still like my previous questions to be answered ) and I also have a few more questions - 5)From what I gathered an object immersed in water experiences a net upward force because the "pressure a liquid exerts increases with depth" so the upward force at the bottom will be more than the downward force at the top resulting in a net upward force.But won't there also be a downward force at the bottom of equal magnitude as the upward force at the bottom.This would mean that the upward force of greater magnitude would be cancelled resulting in no net force ? The only explanation I could come up with is that the downward force of equal magnitude has no surface area on which to act. Is this correct? 6)But what if the object was shaped like a very,very thin disc ? Then the pressure difference would also be extremely small meaning that the difference between the upward force and the downward force would also be very small. And if a long rod like object was placed vertically in water the pressure difference would be very high resulting in a much greater upward force. So, this means that buoyancy depends on the shape of the object. 7)Another question I have is that if the pressure a liquid exerts increases with depth then if you take a object shaped like a upside down pyramid then the pressure at the top will be less but it will have more surface area meaning bigger force whereas at the bottom there will be less surface area therefore less force.So, again buoyancy depends on shape. Please make the answers as simple as possible.