Fluid static problem with wooden block being pulled down

In summary: Archimedes principle states that in a fluid, the weight of an object is the sum of the weight of the liquid and the object itself. So, in this situation, the weight of the metal part is the sum of the weight of the liquid (SG of 0.3) and the metal part itself (6600m^3).
  • #1
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Homework Statement


The figure below shows a metal object (2) hanging by a thin cord from a floating wooden block (1). The wood block has a SG of 0.3 and dimensions of 50mm x 50mm x 10mm. The metal part as a volume of 6600m^3. Find the mass of the metal part and the tension in the cord. Work in gage pressure.

Homework Equations


Specific weight = W / m^3
Pressure = specific weight X h = pgh
W = mg

The Attempt at a Solution


I find pressure on the point at the bottom of the wooden block - P = 9810 X 0.01

If I am not wrong, that is the tension in the cord ? But I am totally unsure on how to go about solving the mass of the metal part. I suspect that I need to use specific weight = W / V since they gave volume. But how am I suppose to find the specific weight ? Thanks..[/B]
 

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  • #2
I suggest starting by identifying the forces acting on each object. What forces act on the wooden block?
 
  • #3
Doc Al said:
I suggest starting by identifying the forces acting on each object. What forces act on the wooden block?

Force acting downwards by its weight and the metal block? The force acting upwards by the cord ? But how these are going to affect my calculations hmm
 
  • #4
tonnieee said:
Force acting downwards by its weight and the metal block?
Three forces act on the wooden block: buoyant force, weight, tension in the cord. What must they add to?

tonnieee said:
But how these are going to affect my calculations hmm
You calculated the pressure at the bottom of the block. Pressure is not a force, for one. And you neglected the weight of the block.
 
  • #5
Doc Al said:
Three forces act on the wooden block: buoyant force, weight, tension in the cord. What must they add to?You calculated the pressure at the bottom of the block. Pressure is not a force, for one. And you neglected the weight of the block.

Is there a way to find the forces ? I was not really taught about this in fluid statics.
 
  • #6
Have you heard of Archimedes principal?
 
  • #7
Chestermiller said:
Have you heard of Archimedes principal?

No
 
  • #8
tonnieee said:
No
Well, you need to learn about that before you can solve this problem.
 
  • #9
Chestermiller said:
Have you heard of Archimedes principal?
He was the head of the school young Archimedes attended, right?
 
  • #10
haruspex said:
He was the head of the school young Archimedes attended, right?
Ha! Good one.
 

1. What is a fluid static problem?

A fluid static problem is a situation in which a fluid, such as water or air, is at rest and is being acted upon by external forces.

2. How is a wooden block involved in a fluid static problem?

In this specific problem, a wooden block is placed on top of the fluid and is being pulled down by a force, causing the fluid to move and creating a fluid static problem.

3. What factors affect the behavior of the fluid in this problem?

The density and viscosity of the fluid, as well as the size and shape of the wooden block, all play a role in the behavior of the fluid in this problem.

4. How can the pressure of the fluid be calculated in this scenario?

The pressure of the fluid can be calculated using the equation P = ρgh, where P is the pressure, ρ is the density of the fluid, g is the acceleration due to gravity, and h is the depth of the fluid.

5. Can this problem be applied to real-life situations?

Yes, this type of fluid static problem can be seen in various real-life scenarios, such as determining the pressure on a submerged object or calculating the force needed to move an object through a fluid.

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