Fluid Mechanics: Density & Balances in Beaker B

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Homework Help Overview

The discussion revolves around a fluid mechanics problem involving the density of a liquid and the forces acting on a submerged block in a beaker. Participants are analyzing the readings from spring balances and the implications of Archimedes' principle in determining the densities involved.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the need to find the density of the block to determine the density of the liquid, suggesting the use of apparent weight and buoyant force equations. Questions arise about the necessity of knowing the liquid type and the setup of equations based on balance readings.

Discussion Status

The discussion includes various attempts to set up equations relating the weights indicated by the balances to the forces acting on the submerged block. Some participants provide guidance on using Archimedes' principle, while others seek clarification on the equations and their components. There is no explicit consensus, and the conversation remains open-ended.

Contextual Notes

Participants are working under the constraints of a homework assignment, which may limit the information they can use or the methods they can apply. The original poster questions whether the identity of the liquid is necessary for solving the problem.

CollectiveRocker
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Block A hangs by a cord from spring balance D and is submerged in a liquid C contained in beaker B. The mass of the beaker is 1.00 kg and the mass of liquid is 1.80 kg. Balance D reads 3.50 kg and balance Balance E( supporting beaker B) reads 7.50 kg. The volume of block A is 3.80 * 10^-3 m^3. a) What is the density of the liquid? b) What will each balance read when Block A is pulled out of liquid? Do I need to know what the liquid is in order to solve this? I know that p(density) = mass/volume. So in this case is it just mass of liquid/volume of liquid?
 
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I suspect that you will need to find the density of the block in order to find the density of the liquid. This can be done by setting up equations for the apparent weight of the block given by balances D and E. Hope that helps.
 
Can you please explain further?
 
Weight loss/Apparent weight=Weight of body-weight of liquid displaced
weight= mass*g = Volume*density*g.
Need any more help?
regards
 
Last edited:
There will be two equations. The first equations will relate the apparent weight of the block given by balance D to the actual weight of the block and the product of the buoyant force (set this up using Archimedes' pricincple). The second equation will relate the weight given by balance E to the weight of beaker B, liquid C and block A. You'll have two equations and two unknowns (one being the density of the block and the other the density of the liquid).
 
e(ho0n3 said:
There will be two equations. The first equations will relate the apparent weight of the block given by balance D to the actual weight of the block and the product of the buoyant force (set this up using Archimedes' pricincple). The second equation will relate the weight given by balance E to the weight of beaker B, liquid C and block A. You'll have two equations and two unknowns (one being the density of the block and the other the density of the liquid).


If you don't mind my asking, can you give me the equations?
 
CollectiveRocker said:
If you don't mind my asking, can you give me the equations?
Why don't you derive the equations and post them here. Then I'll tell you if you're on the right track.
 
w(D) = W(A) * F(B)
W(E) = W(B) + W(liq) + W(A)
 
You might want to explain what those symbols mean. Keep in mind Archimedes' principle.
 
  • #10
w(D) = weight read by Balance D
w(A) = weight of Block A
w(B) = weight of Beaker B
w(C) = weight of liquid C
F(B) = buoyant force
 
  • #11
Why in the world are you multiplying w(A) and F(B)? That makes absolutely no sense. Maybe you should go back to the basics.
 
  • #12
solved it. Thanks fellas
 

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