I've been wondering about how sunken objects would behave if you could instantaneously flip their container with water. Like if you had a bucket filled with normal tap water and you dropped a ball in it. Then SOMEHOW you instantly flip the bucket over such that for just a moment, the water is suspended in midair and the ball is still touching the base of the bucket.
What I want to know is, first of all what would happen? I know that if you drop a bowling ball and a bouncy ball from the same height they'd just about reach the ground at the same time, but what about this scenario? If you "drop" water and an object inside the water at the same height, do they reach the ground simultaneously? Or does the object "float" down the falling water?
Second of all, under what conditions could the object fall first? That's what I'm looking for- what kind of object could fall out of the water and reach the ground before the water does? What difference would there be between the object being a sunken wooden ship and a rock?
Third of all, say we take this experiment to the ocean, where the water pressure gets higher as you go down. If there's an object at the bottom of the ocean and we flip the ocean, how does the pressure affect things?
Best Answer
I want to supplement Emilio's intuitive answer discussing what would happen with some thoughts as to why what you propose in your second part cannot happen.
Let's assume the water is a single entity. In order for the object to accelerate faster than the water, the object needs to have a larger downward acceleration than the water does. This would need to come from a downward net force that is larger than the weight of the object, as in free fall both objects will have the same downward acceleration. Where would this force come from? There is no buoyant force in a free-falling fluid, but even if there were the buoyant force would act upwards on the object, not downwards. Therefore, the best your could even hope for is that the object and the water move together, and this is indeed what happens.
Perhaps the confusion comes from why certain objects normally sink. They aren't pulled down by the water, they are pulled down by gravity. In your everyday scenarios it is just that the fluid impedes this "falling". You could even think of us as all sinking in the Earth's atmosphere. Therefore, in your scenario, it is not the case that because the object is in water suddenly means it wants to move down through the water. The water itself is not the mechanism for why objects sink.