Fluid continuity

[ljc]

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See attached.

Why is the answer here not D? I understand that velocity is inversely proportional to the area, but when fluid falls from C to D, it won't just magically slow down mid-air, will it? Won't the fluid in the smallest cross sectional area (C) simply accelerate at the rate of gravity, and continue to do so once it leaves the funnel? I understand that if this system were horizontal, C would be a no brainer. Am I just misunderstanding something here? I can't picture the fluid deciding to slow down simply because it has more room to spread out.

 

[MT Headed]

If the answer is not D, it's a poorly written/diagrammed question. Continuity scenarios aren't supposed to have air in the pipes like this question does.

 

[MedPR]

Seems like free fall makes the answer D. Bad question imo.

 

[dmf2682]

See attached.

Why is the answer here not D? I understand that velocity is inversely proportional to the area, but when fluid falls from C to D, it won't just magically slow down mid-air, will it? Won't the fluid in the smallest cross sectional area (C) simply accelerate at the rate of gravity, and continue to do so once it leaves the funnel? I understand that if this system were horizontal, C would be a no brainer. Am I just misunderstanding something here? I can't picture the fluid deciding to slow down simply because it has more room to spread out.

I'd say c. It is a bad question, but if the fluid has any viscosity it will stay attached to the end of the funnel briefly before falling into the tube. This is what causes it to spread out, in concert with the fact that its pressure is slightly higher than ambient. When it spreads out its cross sectional area is larger allowing for drag to decelerate the stream. Bad mcat question, but that's what happens.

 

[ljc]

Okay cool, glad I'm not alone. And yea, the reported answer is C, due to continuity.