Fluid Mechanics Problems: Pressure, Diving Depth, and Density Calculations

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Homework Help Overview

The discussion revolves around fluid mechanics problems, specifically focusing on pressure calculations, diving depth, and density relationships in various scenarios involving water and buoyancy. Participants are exploring gauge pressure, absolute pressure, and the density of floating objects.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants attempt to apply fundamental fluid mechanics equations, such as P = pgh and P = P0 + pgh, to solve for pressures and densities. Questions arise regarding the assumptions made in these calculations, particularly concerning atmospheric pressure and the conditions affecting buoyancy.

Discussion Status

Some participants have provided calculations and attempted to clarify the relationships between pressure, depth, and density. However, there is a lack of explicit consensus on certain interpretations, particularly regarding the treatment of atmospheric pressure in the context of diving and buoyancy problems. Guidance is being sought on specific calculations, indicating ongoing exploration of the topics.

Contextual Notes

One participant notes uncertainty about missing units in a problem regarding the volume of a raft, highlighting potential gaps in information necessary for complete calculations. The discussion reflects the constraints of homework rules and the need for further clarification on specific values, such as the density of the raft.

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1)A cup contain 15cm lvl water. A 29cm straw is place into the cup, at the end of the straw is 1cm from the bottom. If a person sucks on the straw, what gauge pressure is needed at the top of the straw to allow the water to run out of the top and into his mouth.

P=pgh
1000(9.8) .29 = 2842 Pa

2) Approximately how deep below the surface of the ocean must a diver go before the absolute pressure on him 2atm.

P=P0 + pgh
2atm= 1atm + 1000(9.8)h 1atm=100000 Pa
100000 Pa= 1000(9.8)h
h=10m

3) A body having a density of 300kg/m^3 is floating in a container of liquid. If 1/3 of the volume of the body remains above the surface of the liquid, what is the density of the liquid?
1/2*300=100kg/m^3
100+300= 400 Kg/m^3
 
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i need advice please
 
anyone?
 
1. P0 = P+ pgh
P = P0 - 1000(9.8) .29
 
P=pgh
2atm=1000(9.8)h shud nt take atmosph press. because inside water it acts in all dir. hence cancels
 
3. P*2/3=300
3/2*300=450
 
ty
I got the last 1 still trying to figure out and may be u can help
10kg raft made of driftwood w/ specific gravity .60 floats on the surface of a calm pond. Density of water = 1000 kg/m^3
Calculate the volume of the raft

Im not sure if the problem missing some unit
I need Density of the raft to calculate the Volume
I don't know how to get there. Any idea?
 

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