Physics question from DM exam

[LowVizWiz]

Unless it is tethered via a chain to a rock on the bottom. Then it's just floating there, desperately trying to reach the surface and the light of day, so that it can look up and see the sun and smile...

You assume it's day time, it could be nighttime and if the object falls to the bottom and there's no one there to hear does it still make a sound?

 

[SparticleBrane]

And yes I will agree -- this question could have been phrased MUCH better.

 

[NudeDiver]

You assume it's day time, it could be nighttime and if the object falls to the bottom and there's no one there to hear does it still make a sound?

Don't be ridiculous. The object is positively buoyant. It has no chance of falling to the bottom.

Shessh - some people.

 

[SparticleBrane]

You assume it's day time, it could be nighttime and if the object falls to the bottom and there's no one there to hear does it still make a sound?

No but the diver that was just handed all that weight is now missing some eardrums...

 

[NudeDiver]

And yes I will agree -- this question could have been phrased MUCH better.

I think the question is phrased just fine. It seems crystal clear - in terms of what the question actually asks. Now, whether or not it asks what the author intended for it to ask is a different matter. Unless the author wants to come on here and clarify, we have no way of knowing.

 

[Gombessa]

What amount of lead ... would be required to add 20kg/50 lbs of negative buoyancy to the object?

Isomeone hands you 50lbs of lead, "adding 50lbs of negative buoyancy to you..."

Someone hands you 50lbs of lead, again, "adding 50lbs of negative buoyancy to you"

Therein lies the rub, see? 50# is the answer to the question posed, even you agree. The problem is, I don't think anyone will disagree that the question posed is not the question intended.

Btw, I think 50# would have been the best LSAT answer to the question.

 

[NudeDiver]

The intent of the question is irrelevant. All that matters in terms of the correct answer is that it matches what the question ACTUALLY asks.

 

[SparticleBrane]

Therein lies the rub, see? 50# is the answer to the question posed, even you agree. The problem is, I don't think anyone will disagree that the question posed is not the question intended.

Ah but see I just used those numbers as an example.

To add 50lbs of negative buoyancy to something that is already positive, first you have to overcome the amount which the object is positive -- thus, in this case, you need to add 53lbs of lead to add 50lbs of negative buoyancy.

 

[kadleck]

The problem is, I don't think anyone will disagree that the question posed is not the question intended.

You got that right.

 

[Gombessa]

Ah but see I just used those numbers as an example.

Regardless, if you disregard the displacement on the lead as the question asks, the numbers used are representative and accurate. 50# of lead = 50# negative buoyancy, full stop, whether it's to a diver or some imaginary object that's buoyant yet lies on the bottom in 56ft depth.

My question is, can we make some tanks out of that material?