Test your buoyancy understanding!

[The Chairman]

True, but I wouldn't know how to farm, and I am still dependant on farmers for all my food.

And I don't know how to plumb, but I rely on plumbers to take care of my crap.

 

[Tigerman]

I thought snowbound fortresses didnt have plumbing and that you as such relied on lawyers to handle the crap?

 

[eponym]

We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology - Carl Sagan

Legend* has it that J. Robert Oppenheimer was posed this buoyancy question (tossing a rock out of a boat) and got it wrong.

* Okay, actually the TV program Nova

 

[Tigerman]

Well, oppenheimer obviously had no clue about science

 

[eponym]

Well, oppenheimer obviously had no clue about science

And Decartes is rumoured to have said, "I don't know maths from a hole in the ground."

 

[NAM001]

what will change the level of the pool more 100 lbs of lead or 100 lbs of aluminum.. when submerged it is the displacement of the item not the weight

and then the same question with a 1 cu container with 100 lbs of leas and the other with 1oo lbs of aluminum. which will raise the pool level more

 

[windapp]

what will change the level of the pool more 100 lbs of lead or 100 lbs of aluminum.. when submerged it is the displacement of the item not the weight

and then the same question with a 1 cu container with 100 lbs of leas and the other with 1oo lbs of aluminum. which will raise the pool level more

The denser the material, the more the change in volume for this problem.

For the first case, lead will change the level more.

For the second case, the materials are encased in a box making them constant volume. Same volume, and same weight = same density. In this case, the level will change the same.

 

[NAM001]

i agree 100 % and that is the answer to the original post. the answer that it will remain the same iss only correct if the displacement of the rock is same weight as the rock. and that is not the case so when the rock is tossed overboard the water level will drop. in other words a 50 lb one gallon rock in a boat displaces 50 lbs while in the boat. it displaces 8 lbs in the water, allowing the water level to drop when thrown overboard. its kind of the same as what weighs more , a lb of lead or feathers. with bouyancy it is what displaces more, a container of lead or a container of feathers. and it is neither it is the container displacement.

 

[Tigerman]

Maintenance departement confirmed my theory. Tiles will break and they will "skin me alive and beat me to death with it" if I test it..

 

[nimoh]

The denser the material, the more the change in volume for this problem.


For the first case, lead will change the level more.


For the second case, the materials are encased in a box making them constant volume. Same volume, and same weight = same density. In this case, the level will change the same.

I think you have that backwards, the aluminum is a greater volume and will cause a greater change