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No delay. Clasically, the atoms at the point of of contact have a large acceleration,
which decreases as they experience interatomic forces. Their initial motion is therfore
large, and the CM accelerates accordingly. The displacements propagate as a
compression wave at the speed of sound.
As a simple model, consider 2 masses separated by a spring resting on a frictionless
surface. Exert a constant force on one of them for a short time. The motions can
be solved for analytically.
Al Bachman
From: bernardcleyet@redshift.com
Date: Wed, 1 Dec 2010 16:07:36 -0800
To: phys-l@carnot.physics.buffalo.edu
Subject: Re: [Phys-l] The "why" questions
For an extended object, I think there is a delay in the acceleration of the C of M -- the delay is due to the finite speed of sound.
bc, naive?
p.s. Would there also be a delay at the front from the electrostatic repulsion (contact) -- here a bit shorter related to C?
p.p.s. I do believe N laws are symmetrical and imply nothing and work as such macroscopically -- microscopically?
On 2010, Nov 29, , at 13:29, Scott Orshan wrote:
The argument was also made that using cause-effect language might lead
students to believe that there is some delay between force and
acceleration.