Physics Archimedes Principle Distance an object sinks

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Homework Help Overview

The discussion revolves around a block of wood and its behavior when submerged in water, specifically focusing on how far it will sink based on Archimedes' Principle. The problem involves calculating the volume, mass, and density of the block, as well as comparing it to the density of water.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the calculations of volume, mass, and density of the block, questioning the interpretation of the 52.5% sinking statement. There are inquiries about how to determine the volume submerged and the implications of the densities of the block and water.

Discussion Status

Some participants are seeking clarification on the meaning of the 52.5% figure and how it relates to the sinking depth. Others suggest using Archimedes' Principle to find the draft of the block, indicating a shift towards a more useful application of the principles involved.

Contextual Notes

There is an ongoing exploration of the relationship between the densities of the block and water, and how these affect the sinking behavior. Participants are also considering the implications of the block's dimensions and weight in relation to buoyancy.

nwmyname
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Homework Statement


A block of wood measures 2.2m by 2.5m with depth 3.6m with weight 102KN. When placed in water, how far will it sink?

g = 9.81 ms-2
density of water = 1000kg m-3

Homework Equations

The Attempt at a Solution


Volume = 2.2(2.5)(3.6) = 19.8m3
Mass = 102000 / 9.81 = 10398 kg (nearest whole)
Density = 10398 / 19.8 = 525 kg m3

It sinks 52.5% of the water.

How to continue finding how far it will sink?
 
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nwmyname said:
It sinks 52.5% of the water.
Please explain what you mean by that statement.
 
haruspex said:
Please explain what you mean by that statement.
The density of the object is 525 kgm-3 and the density of the water is 1000 kgm-3 so it must be sink 52.5% into the water?
 
nwmyname said:
The density of the object is 525 kgm-3 and the density of the water is 1000 kgm-3 so it must be sink 52.5% into the water?
How much volume is below water?
 
nwmyname said:

Homework Statement


A block of wood measures 2.2m by 2.5m with depth 3.6m with weight 102KN. When placed in water, how far will it sink?

g = 9.81 ms-2
density of water = 1000kg m-3

Homework Equations

The Attempt at a Solution


Volume = 2.2(2.5)(3.6) = 19.8m3
Mass = 102000 / 9.81 = 10398 kg (nearest whole)
Density = 10398 / 19.8 = 525 kg m3

It sinks 52.5% of the water.

How to continue finding how far it will sink?
A much more useful application of Archimedes' Principle would be to find out the draft that the block must float at such that the weight of water displaced by the block is equal to the weight of the block itself. The draft of the block is that distance the bottom sinks below the surface of the water, and given the shape of the block, a trivial calculation.
 
nwmyname said:
The density of the object is 525 kgm-3 and the density of the water is 1000 kgm-3 so it must be sink 52.5% into the water?
It sinks 52.5% of what into the water? 52.5% of the block?
 
d = (pB/pw)h
d is the distance it sinks in the water.
h is the height of the object.
pB is the density of object
pw is the density of water
 

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