⟩ If you are on a boat and you throw out a suitcase, will the level of water increase?
It depends on the density of the briefcase.
While the briefcase is in the boat, it will displace it’s
weight in water.
If the briefcase floats after you toss it out, then it still
displaces its weight in water, and there is no change.
However, if the briefcase is heavier than water it will
displace its volume, not its weight. The amount of displaced
water will be less (which is why it sank) and the water
level will decrease.
