Re: [Phys-l] Errata for FCI?

[chuck britton <cvbritton@mac.com>]

Thank you for resurrecting this 'sticky' subject.
I have yet to see the concise argument against D.
If we are going to use the term 'Bouyancy', do we need a definition 
other than the Archemdian 'weight of displaced fluid'??
What might that new, PC (Pedagogically Correct) definition be??

.
At 9:00 PM +0800 11/3/10, carmelo@pacific.net.sg wrote:
> Actually, I am still looking for a more appropriate microscopic 
> definition on buoyant force. Besides, it seems that many physics 
> teachers and physics education researchers have misconception on 
> buoyant force. Perhaps, there should be errata published for numerous 
> research papers on Force Concept Inventory (FCI)? Please refer to the 
> question below.
>
> A book is at rest on a table top. Which of the following force(s) 
> is(are) acting on the book?
> 1. A downward force due to gravity.
> 2. The upward force by the table.
> 3. A net downward force due to air pressure.
> 4. A net upward force due to air pressure.
>
> A 1 only.
> B 1 and 2
> C 1, 2, and 3.
> D 1, 2, and 4.
> E none of these, since the book is at rest there are no forces acting on it.
>
> In many papers on FCI, the answer is D based on the definition that 
> buoyant force is the magnitude of the weight of fluid displaced by the 
> body. Perhaps, analysis should be carried out again on FCI based on
> the answer C instead? Some of you may prefer B to be the answer? :-)