Re: Free Body Diagram

[John Clement <clement@HAL-PC.ORG>]

> In David Albineri's original question, the problem of correctly
> identifying the acceleration for the gravity-aligned system is manifest.
> The problem with this free body diagram is not the diagram, but the
> assumption that the vertical acceleration is zero.  The vertical
> acceleration in this diagram is -gsin^2(th).  Where in the world did
> this come from?

As I pointed out is an extremely common misconception (70%> ?)  after
conventional instruction that acceleration goes to zero when the velocity
goes to zero.  This is resistant to change even after labs which clearly
show this is not true.  Students who are formal operational thinkers will
usually change their conception after the appropriate labs, but concrete
operational students often do not.  Conventional instruction has practically
no effect on this conception.

John M. Clement
Houston, TX

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.