if a beaker was filled with 200 cc of water and we tethered a ping pong ball to it's floor and that ping pong ball size is 10 cc .
Q1: what will be the weight of the beaker at that time ? (ignore the empty weight, ball and thread)
A1 : 200 grams
Q2: what will be the weight of the beaker at the first few milliseconds if we cut the thread ?
A2: 210 grams
(for the next analysis , suppose that the ball is like balloon and we just popped it with a needle so the air inside it is free)
for those who agree, they might explain it by the buoyancy force of the ball acting against the water. but the ball is almost weightless (presumed with no weight in this experiment , think of it as air bubble) , so how come a weightless object (say 0.0122 grams) can cause a reaction of 10 grams ?
the way i see it is that it all depends on the total water pressure acting on the beaker floor and that force is 210 before and after the thread being cut or the balloon exploded but in the first case there was upward tension of the thread acting on the beaker while in second case, that tension was gone.