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So a bob is dipped into the water.
Should that side be heavier because of the bob’s “downthrust” (the downward action-reaction buddy of the upthrust force that the water exerts on the bob)?
Or should that side be lighter because of the missing (displaced) water’s weight?
Guess that, the “downthrust” is equal in magnitude to the missing (displaced) water’s weight!
Water has this amazing ability to spread the weight uniformly!
The balance is broken when the bob touches the bottom of the container. The additional downward normal contact force tips the balance.
xmDemo 