Solve Force & Buoyancy: 1000N to Lift Concrete Block Out of Water

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Homework Help Overview

The discussion revolves around a physics problem involving forces and buoyancy, specifically relating to a concrete block submerged in water. The original poster seeks assistance in determining the force required to lift the block out of the water, given that a force of 1000N is needed to raise it to the surface.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the forces acting on the block, including weight, buoyancy, and the applied force. There are inquiries about the volume of the block and the relevance of its density in solving the problem.

Discussion Status

The discussion is ongoing, with participants exploring different aspects of the problem. Some guidance has been offered regarding the forces involved, but there is no clear consensus on how to proceed without additional information, such as the block's volume.

Contextual Notes

Key constraints include the lack of information about the block's volume, which is critical for calculating the forces accurately. The only given data is the 1000N force and the density of concrete.

srfrgrl727
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Can anyone help me out. I don't know of any equation that i can us eto solve this A force 1000N is required to raise a concrete block to the surface of a fresh wate rlake. what is the force required to lift it out of the lake. I know that i need to figure out what the weight outside of wate ris, but i don't know how. no i don't know the volume the 1000N is the only info given. density is 2320 kg/m3.
 
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If you draw a free body diagram of the block under water you should have three forces acting on it: The block's weight, the buoyancy force and the 1000N applied force. This should tell you that the force required to lift the block in air will equal the buoyant force + 1000N.

Do you know the volume of the block?
 
srfrgrl727 said:
no i don't know the volume the 1000N is the only info given.
But are you given the density of concrete?
 
The Force you need to raise the block with the volume [tex]V[/tex] to the surface is
[tex]F_1=gV(\rho_{concrete}-\rho_{water})[/tex]
the force to raise the block futher is

[tex]F_2=gV\rho_{concrete}[/tex]

Then [tex]\frac{F_2}{F_1}=[/tex]
 
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