Momentarily Displacement Force
Any matter ingested in fluid container will cause the fluid level to rise, increasing the pressure on the container's floor, when that pressure is multiplied to the floor area, that would be the forces towards the acceleration (gravity) .
A simple example for that is a balloon tethered to the floor of a water tank, the downward force will increase with an amount equal to the balloon size (displacement), however there's another upward force caused by the balloon pulling up on the tank floor with a force equal to the balloon displacement, hence the tank weight doesn't change until the thread is cut, the upward force is removed and only the extra downward force remain temporarily for limited time governed by a group of factors, primarily the balloon reaching the surface or reaching its terminal velocity.
Momentarily Displacement Force Experiment
the experiment illustrated in the Fig below is to prove the momentarily displacement force
a water tank filled with 20 L of water
a 1000 cc block of iron (density of 8 Gm/cc)
a 1000 cc balloon tethered to the iron block
weighing scale
phase 1 : before tethering the balloon
water weight = 20kg
iron block displacement = 1kg
iron block force on the tank's floor =7kg
total scale reading = 28kg
phase 2 : after tethering the balloon
water weight = 20kg
iron block displacement = 1kg
balloon displacement = 1kg
iron block force on the tank's floor = 6kg
total scale reading = 28kg
phase 3 : momentarily after releasing the balloon
water weight = 20kg
iron block displacement = 1kg
balloon displacement = 1kg
iron block force on the tank's floor =7kg
total scale reading = 29kg
final phase
the balloon reach the surface or its terminal velocity and the effect is gone, back to phase 1