Date: Fri, 6 May 2011 22:12:40 +

Author: --- "Simcha Segev"

Subject: Re: Invisible force - stick-slip motion demo

Post:

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Paul,



I cannot change the direction of the card movement to be opposite to my hand
motion. The Principle of this "trick" is that because the different in the
static - kinetic friction of my hand with the wire. The card friction has
nothing to do with that. The only thing that is related to the card is it
Inertia conservation. Actually the wire moves in some saw tooth movement.
Raising slowly in the direction of my hand movement and "jumping" back when
the static friction came to the point that changed to kinetic friction.



Greetings, Simcha





From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Paul Nord
Sent: Friday, May 06, 2011 7:57 PM
To: tap-l@lists.ncsu.edu
Cc: Paul Nord
Subject: Re: [tap-l] Invisible force - stick-slip motion demo



Simcha,



I saw that yesterday. Very nice.



Question for you: Can you make the card go in a direction opposite to the
motion of your hand? Perhaps at a certain frequency of the stick/slip
cycle? Or, perhaps by changing the frictional characteristics of the card?
Tuning the mass of the card so that it goes into some other resonance with
the fishing line?



I'm picturing something like the old propeller on a notched stick:

Toys, Making a Whammy Diddle



Paul





On May 6, 2011, at 11:38 AM, Simcha Segev wrote:





Hi all,



A phenomenon discussed in the theoretical exam on the Asian physics Olympiad
2011

http://www.youtube.com/watch?v=3_WLrWh0-W0



The slip-stick motion mode (high-frequency sine/linear motion interchanging
fast due to the difference between static and kinetic friction combined with
elasticity) create a sawtooth-like movement, used to move distant objects.



Have a nice and pleasant weekend, Simcha







Simcha Segev - Technical Manager

Physics Demonstration Lab

School of Physics and Astronomy

Tel Aviv University, Ramat aviv, Israel

Tel. 972-3-6408077 Fax. 972-3-6429306

E-mail: simcha@post.tau.ac.il

Web site : http://www.tau.ac.il/~simcha






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Paul,=
=
I cannot =
change the direction of the card movement to be opposite to my hand =
motion. The Principle of this "trick" is that because the =
different in the static kinetic friction of my hand with the =
wire. The card friction has nothing to do with that. The only thing that =
is related to the card is it Inertia conservation=
. Actually =
the wire moves in some saw tooth movement. Raising slowly in the =
direction of my hand movement and "jumping" back when the =
static friction came to the point that changed to kinetic =
friction. =
Greetings, =
Simcha =
From:=
=
tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On =
Behalf Of Paul NordSent: Friday, May 06, 2011 7:57 =
PMTo: tap-l@lists.ncsu.eduCc: Paul =
NordSubject: Re: [tap-l] Invisible force - stick-slip motion =
demo Simcha, I =
saw that yesterday. Very nice. Question for you: Can you make the card go in a =
direction opposite to the motion of your hand? Perhaps at a =
certain frequency of the stick/slip cycle? Or, perhaps by changing =
the frictional characteristics of the card? Tuning the mass of the =
card so that it goes into some other resonance with the fishing =
line? I'm picturing something like the old propeller on a =
notched stick:Toys, Making a Whammy =
Diddle Paul On =
May 6, 2011, at 11:38 AM, Simcha Segev wrote:Hi =
all, =
=
A phenomenon =
discussed in the theoretical exam on the Asian physics Olympiad =
2011=
http://www.youtube.=
com/watch?v=3D3_WLrWh0-W0=
=
=
The =
slip-stick motion mode (high-frequency sine/linear motion interchanging =
fast due to the difference between static and kinetic friction combined =
with elasticity) create a sawtooth-like movement, used to move distant =
objects.=
=
=
Have a nice =
and pleasant weekend, Simcha=
=
=
=
=
Si=
mcha Segev&n=
bsp; - Technical Manager=
Ph=
ysics Demonstration Lab=
Sc=
hool of Physics and =
Astronomy=
Te=
l Aviv University, Ramat aviv, =
Israel=
Te=
l. 972-3-6408077 Fax. 972-3-6429306=
E-=
mail: &n=
bsp; simcha@post.t=
au.ac.ilWe=
b site : =
http://www.tau.ac.il/~simcha =

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