Re: free-body diagrams

[Leigh Palmer <palmer@SFU.CA>]

> Of course, it is utterly negligible; and I comment on that.  It just bothers
> me that I pound my fists on the table saying that you *must* identify all
> forces in order for the free-body procedure to work and then one manifestly
> leaves out some forces that we know are present (even if negigible).

I get around that by not defining a force of gravity*; the blocks
only have weight. Another point I might note is that, realistically,
the electromagnetic forces of contact will exceed gravitational
forces in most real cases. If you can neglect one (ignoring friction)
you can certainly ignore a smaller one.

Leigh

*to appear shortly in response to Joel's earlier note