Physics problem

[Phred]

Okay,

So your in a boat in the middle of a lake. Inside the boat is an iron anchor - not attached to a rope.

You throw the anchor into the water and obviously it sinks to the bottom.

My question is this, at point is the water level of the lake the highest (when measured against the shore, <b>not</b> the boat). When the anchor is in the boat or when it is in the water. Or, are they both the same?

Note - I am Assuming that you could actually measure any minute difference here. Also, this lake has no fish, or plants or mud or anything else to interfere with the measurement.

Phred

[bradm]

Does this help:

Objects immersed in water displace their volume, but objects floating in water (e.g., in a boat) displace their weight.

(Or you could try it yourself: take a toy boat and a sink, and press down on it with your hand, and watch the water level as you press down to the point just before it sinks, and just after.)

Aloha,

Brad

[Guest Low Roller]

The solution is to find out which scenario displaces more water:

Scenario A: total surface area of submerged boat with anchor

Scenario B: total surface area of submerged boat plus total surface area of the anchor

I don't think we are given enough information to solve the problem.

[bradm]

Is this today's heady survivor immunity challenge question, or, you know, are you on a ship somewhere accessing the 'net remotely, and need an answer before the lifeboats are all gone?

Aloha,

Brad

[Guest Low Roller]

Ima cooking sumpting up....

[The_eKuhnunist]

In my mind, the anchor should be a whole lot more dense than the boat. The more dense something is, the less volume it displaces/weight. Hence, when it's in the boat, it causes the boat to displace more water (because we're using the boat's volume), and when it's submerged the anchor's displacement + the boat's (lessened) displacement should end up being less.

Did that make sense?

[Thorgnor]

Yes, eK... it does make sense and my vote is with you.

[jazzinfivefour]

Because the size of the vessel (boat), the body (water) will be displaced less because of it's greater surface contact while the object (anchor) is contained within it. Therfor, when the object is emmersed into the body, a greater amount of displacement will take place. They used to measure the kings crowns in this way in order to decide the density of the gold, in turn determining the crowns value.

Time of day would greatly influence this examination due to the gravitational effects a moon has upon a spinning planet and it's bodies of water. And since our results would be so minimal in measurement, we would also have to consider the natural creation of gases in the water which would affect fluid displacement. ohh and factory pollutions being dumped into the water, which we wouldn't be aware of because those bastards do those evil deeds secretly.

[long time runnin']

There's a higher water level on the shore when the anchor is in the boat!!

Think of the anchor's force on the bottom of the boat, which results in pushing the boat down, and bringing the water level up.

Now think of the force on the bottom of the lake with the anchor in it. This force cannot push the lake bottom down, so the anchor can only displace it's volume.

Someone else here had this answer, which is correct

[Phred]

Some of you got it. (LR - I did give enough info when I said that the anchor sunk).

Density = Mass/Volume. Water has a density of 1. since the anchor sunk, m > v.

It displaces based on its mass while in the boat, and volume while at the bottom. since m > v, it displace more water when the anchor is in the boat.

[Guest Low Roller]

I guess I'm pretty dense for not getting that.