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Re: MOMENT OF INERTIA

Picture a flat-bed truck accelerating while carrying a heavy safe, on a
level road. The net force on the safe is a static horizontal force from
the truck floor. This force is the mechanism whereby the kinetic energy
of the safe is increased.

(In static friction, there is no RELATIVE motion of the two surfaces
involved.)

Bob Sciamanda
Physics, Edinboro Univ of PA (ret)
trebor@velocity.net
http://www.velocity.net/~trebor

-----Original Message-----
From: Jerome Epstein <jerepst@WORLDNET.ATT.NET>
To: PHYS-L@LISTS.NAU.EDU <PHYS-L@LISTS.NAU.EDU>
Date: Saturday, December 19, 1998 10:02 PM
Subject: Re: MOMENT OF INERTIA
. . .

Friction can NEVER cause an increase in speed. Static friction only
opposes outside forces and there is no motion at all (static).
. . .
J. Epstein