[Phys-l] Errata for FCI?

[carmelo@pacific.net.sg]

M. Horton wrote:
> I agree that the original question may not have been asking what it  
> intended  > to ask.  So, I'll ask what I think the original  
> questioner was intending to  > ask because I've long had the same  
> question.  (Wow, >that was confusing.)    > Where does the buoyant  
> force come from?

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? :-)


Best regards,
Alphonsus