Fluid static problem with wooden block being pulled down

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
Sign up Log in
9 replies · 3K views
tonnieee
Messages
4
Reaction score
0

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]
 

Attachments

  • 40461CD3-0B40-4B69-8357-03BCFCD55BDC.jpeg
    40461CD3-0B40-4B69-8357-03BCFCD55BDC.jpeg
    14.1 KB · Views: 590

Discussion

Physics news on Phys.org
I suggest starting by identifying the forces acting on each object. What forces act on the wooden block?
 
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
 
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.
 
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.
 
Chestermiller said:
Have you heard of Archimedes principal?

No