Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: Am I pushing your leg? (Was: CAUSATION IN PHYSICS)



----- Original Message -----
From: "John Mallinckrodt" <ajmallinckro@CSUPOMONA.EDU>



So what distinguishes a push from a pull? Is it where the "agent"
is located? That seems a little tortured in this case. And even
if so, what *is* the agent here? Or is it that "pushes cause
compression" and "pulls cause tension"? I think any definition,
no matter how unambiguous, will fail the "common sense test" in
certain circumstances. Fortunately, it is seldom if ever a useful
distinction anyway.


I find that students can't even use 'common sense' to distinguish pushes
from pulls (and their directions). Every year when we're doing N3, I get
lots of incorrect statements in simple, unambiguous situations. For
example, I'll often see 'the Earth pushes down on the ball' for the
gravitational force (perhaps understandable) and 'the table pushes down on
the book' (which is not). Students will _often_ say that A pushes down on B
even if B is above A. To me, it is 'common sense' that this can't be so.
They often confuse push for pull and pull for push despite the 'common
sense' English application of the words. I'm not sure how critical this all
is to understanding the Physics (somewhat important I think) but students
sure have trouble with it!

Rick

**************************************************
Richard W. Tarara
Associate Professor of Physics
Department of Chemistry & Physics
Saint Mary's College
Notre Dame, IN 46556
219-284-4664
rtarara@saintmarys.edu

FREE Physics Instructional Software
www.saintmarys.edu/~rtarara

Win9.x, WinNT/2000, Win3.x, Dos, Mac, and PowerMac
New: E&M package.
New: PowerMac software updates.
Windows and Mac CD-ROMs now available.
****************************************************