Re: work done by friction

[John Denker <jsd@MONMOUTH.COM>]

At 01:52 PM 10/26/99 +1000, Brian McInnes wrote:
> John and Chuck have both presented illustrations to show that
> frictional forces do work.  John's illustration is the hand wiped
> across the table top and Chuck's illustration is a box being dropped
> on to a moving conveyor belt.
>
> ... relative motion ...
>
> John's and Chuck's examples are not of this [relative motion] kind.

I disagree.

> These is no relative
> motion between the hand and the table or the box and the belt.

In my previous note I explicitly stated that the hand was *wiped* across
the tabletop and explicitly stated that there *was* relative motion between
the two.

> John, you write: "I don't care how many experts claim it. The claim is
> not correct."  I'll meet you for the situation where the is no
> slippage involved; will you think again about the slippage situation?

I hereby think about it for the Nth time and reject the claim yet again.  I
assert yet again that dynamic friction does work in the cases Chuck and I
have described.

> In the "static" situation illustrated in your figure,

To repeat:  I explicitly discussed dynamic not static friction.

______________________________________________________________
copyright (C) 1999 John S. Denker             jsd@monmouth.com