Reply to: Riddles

[richard-af]

What if the rock had inclusions that were soluble?

[Diver]

I was a bit slow in posting that follow up wasn't I
Somebody beat me to it

[Diver]

Now!
Let's factor in the consistency & density of the bottom of the pond ?
The depth of the pond over specific gravity of the water ?
(average 0.445 Lb's per square inch for salt water 0.433 for fresh, brackish anywhere between)
The specific volume over density/weight of the rock ?
The ammount of turbulance/wave action caused by depositing the rock in the water. (waves that carry water up the banks of the pond that cause depletion) ?
The porosity of the material that constitutes the rock ?
The adherence of water to the hull of the vessel as weight is lessened and the hull rises in the water ?
The Heizenberg uncertainty principle

Oh it is not a perfect world. - Never ever deal in absolutes

[Pinto]

Cheers

[MrRobin]

While the rock is in the boat, it's displacing water by weight, once the rock hits the bottom, it's displacing water by volume.

As the rock is heavier than the weight of water displaced by its volume, otherwise it would not sink, the water level would drop?

Yes! Well done have a star

*

[MrRobin]

Well, I'll put you all out of your misery then. The water level drops, this is why:

Whilst the rock is in the boat, the volume of water displaced is proportional to the rock's weight. When it is in the water, the volume of water displaced is just equal to the rock's volume. Since the density of the rock is more than the water (because it sinks), the volume of water to support the weight of the rock is more then the volume of the rock itself and therefore less water is displaced and the level drops.

Easy when you know how and now you'll be prepared for interviews at Burdock's client.

[Pinto]

While the rock is in the boat, it's displacing water by weight, once the rock hits the bottom, it's displacing water by volume.

As the rock is heavier than the weight of water displaced by its volume, otherwise it would not sink, the water level would drop?

[Clippy]

<Roy Walker>It's good but it's not right</Roy Walker>

Stays the same as the same amount of water is displaced regardless of whether the rock is in the boat or in the pond.

[MrRobin]

You're almost there Kyajae but you don't need any more info about the rock.

Hint:

it quickly sinks to the bottom

[Kyajae]

<Roy Walker>It's good but it's not right</Roy Walker>

The displacement of the water by the hull of the boat will depend on a) your weight and b) the weight of the rock.

The moment the rock leaves the boat but immediately before it hits the water and sinks to the bottom, the water level would go down since the boat is displacing less water (i.e. less weight).

When the rock hits the water and sinks, the water level in the pond will rise, but without knowing more about the rock, it's impossible to say if the water level will rise to below, the same or higher than the level it was at at the very start.

Or am I making this too complicated?

[MrRobin]

Water level would remain the same, the displacement created by the hull of the boat would decrease to the same volume as the diplacement created by volume of the rock.

<Roy Walker>It's good but it's not right</Roy Walker>

[Diver]

Here's a good brainteaser

You're standing in a small boat on a small pond and also in the boat is a large heavy rock. You pick the rock up and chuck it in the water and it quickly sinks to the bottom.

Does the water level on the pond rise, fall or stay the same?

Water level would remain the same, the displacement created by the hull of the boat would decrease to the same volume as the diplacement created by volume of the rock.
in a perfect world that is

[Burdock]

Here's a good brainteaser

You're standing in a small boat on a small pond and also in the boat is a large heavy rock. You pick the rock up and chuck it in the water and it quickly sinks to the bottom.

Does the water level on the pond rise, fall or stay the same?

I was asked this at a job interview!!! I stammered and stuttered for 10 mins...and got it wrong...only just tho

[MrRobin]

Here's a good brainteaser

You're standing in a small boat on a small pond and also in the boat is a large heavy rock. You pick the rock up and chuck it in the water and it quickly sinks to the bottom.

Does the water level on the pond rise, fall or stay the same?

[Burdock]

St John's Wood?

you cheating hound!!!