Upthrust

Why is it that the upwards force acting on the bottom of an object submerged in a liquid is greater than the downward force from the top? I understand that the deeper an object is submerged in a liquid, the more force it will experience due to the weight of the particles above it, but weight acts downwards so I don't understand how that contributes to upthrust. The only other thing I can think of could be the collisions of the liquid particles on the bottom being greater than those at the top but that doesn't make much sense since there are more particles above the object than below so the collisions would be greater on the top surely?

Reply 1

RebeccachemPT

2

Original post by DedBread

Why is it that the upwards force acting on the bottom of an object submerged in a liquid is greater than the downward force from the top? I understand that the deeper an object is submerged in a liquid, the more force it will experience due to the weight of the particles above it, but weight acts downwards so I don't understand how that contributes to upthrust. The only other thing I can think of could be the collisions of the liquid particles on the bottom being greater than those at the top but that doesn't make much sense since there are more particles above the object than below so the collisions would be greater on the top surely?

It sounds to me like you are nearly there. The only thing is that the pressure of a liquid acts in all directions equally, so because the bottom of the object is deeper down it experiences more pressure on it than the top of the object, hence upthrust.