Understanding Submerged vs Underwater Objects: A Quiz and Explanation

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Discussion Overview

The discussion revolves around the behavior of submerged and underwater objects, specifically focusing on a scenario involving a boat and a dense ball in an enclosed pool. Participants explore the implications of density on buoyancy and water displacement, as well as the effects on water surface levels relative to the bank and the boat.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant states that an object with a density smaller than water will float, while one with the same density will be submerged, and one denser will sink to the bottom.
  • Another participant claims that when the dense ball touches the bottom, the water level will rise relative to the bank, but the boat will rise with it, resulting in no change relative to the boat.
  • A participant questions why the water level would only rise when the ball touches the bottom, suggesting that the ball displaces the same amount of water while sinking as when it is at the bottom.
  • A later reply clarifies that the water level rises when the ball is initially inserted due to displacement, but this does not affect the buoyancy equilibrium of the boat.

Areas of Agreement / Disagreement

Participants express differing views on when the water level rises and the effects of the ball's displacement on the boat's buoyancy. There is no consensus on the timing of the water level change relative to the ball's position.

Contextual Notes

Some assumptions regarding the mechanics of buoyancy and water displacement may not be fully articulated, and the discussion does not resolve the complexities surrounding the buoyancy of the ball.

wavingerwin
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i understand that an object with smaller density than water will float on water
with the same density, it will be submerged and "suspended" in the middle of the water

my question is in the case of an object being denser than water, it will sink and finally touches the ground (underwater).

i did a quiz 6 months ago and try to recall a question (picture attached)
A boat floating on an enclosed pool while a ball of a big density is sinking.
When the ball is finally underwater i.e. touches the pool's bottom,
What will happen to the water's surface?
1.relative to the bank
2.and relative to the boat
I forget what the answer was, can somebody please help?

thank you!
 

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The water will rise relative to the bank but the boat will rise with it so that relative to the boat there is no difference.
 
The water will rise relative to the bank but the boat will rise with it so that relative to the boat there is no difference.

Can you please explain why?
why would it rise only when the ball finally touches the ground?
since the ball displaces the same amount of water while sinking and while being underwater (at the bottom of the pool), would it be the same surface level when the ball is sinking and underwater?
:rolleyes:

Thank you very much!
 
Sorry, I should have clarified. The water won't rise when the ball hits the bottom, it'll rise when you initially insert the ball. When that happens it displaces its volume worth of water which will lead to the water level rising. However, this will not effect the bouyancy equilibrium of displaced water to bouyancy force for hte boat and thus its level of submersion will remain the same. The life of the iron ball is a little more complicated, however that's not part of the question
 

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