Date: Sat Apr 28 14:41:13 2007

Author: Richard Heckathorn

Subject: Re: Newton's Cradle

Post:
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Greetings,

=20

You spoke about raising 2 balls and only 2 balls
move out the other side.=20

=20

What if you pull back 3?

=20

What if you pull back 4?

=20

What if you pull one ball back on one side and one
ball back on other side?

=20

What if you pull two balls back on one side and
three on the other side?

=20

Repeat for all other possibilities.

=20

In each condition there is a conservation of
momentum.

=20

What about the conservation of kinetic energy?

=20

My first question is it an elastic or inelastic
collision.

=20

To answer that, pull one ball back and have one
other ball at rest. (hold the other three so they
are out of the way).=20

=20

My observation indicates that it is conserved or
very nearly so.

=20

Thus for both momentum (mv) and kinetic energy
(1/2mv2) to both be conserved, the after must be
conserved.

=20

If you have some old pool balls, make a larger
apparatus out of them. Or you could even use
bowling balls of same mass.

=20

=20

Hope this helps

=20

Dick

=20

=20

Helping teachers who facilitate, motivating
students who learn.

Dick Heckathorn 14665 Pawnee Trail Middleburg
Hts, OH 44130 440-826-0834

www.cvcaroyals.org/~rheckathorn/

Adjunct Physics Teacher - Baldwin Wallace College

Physics is learning how to communicate with ones
environment so that it will talk back.

=20

=20

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu
[mailto:tap-l-owner@lists.ncsu.edu] On Behalf Of
William Beaty
Sent: Saturday, April 28, 2007 2:00 PM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Newton's Cradle

=20

On Sat, 28 Apr 2007, Borislaw Bilash wrote:

=20

> 1] When ball 1 & 2 are lifted and then relased
why do balls 4 & 5 rise

> up, rather than only ball 5 travelling at twice
the speed?

>

> 2] why does ball 3 not move? (not the same
question, as 1)

=20

Pretend that there are small gaps between all the
balls. The cradle still

works the same, which shows that all the
collisions only involve two balls

hitting each other, not two balls hitting a third.
Drop one ball in, and

it hits the next, which moves and hits the next,
etc. Drop two

closely-spaced balls in and think about what
should happen.

=20

Or better yet, modify your actual Newton's Cradle
so the balls are not

touching each other. Put 1mm gaps between. Then
it goes "zip zip zip"

rather than "clack clack clack."

=20

=20

=20

(((((((((((((((((( ( ( ( ( (O) ) ) ) )
)))))))))))))))))))

William J. Beaty
SCIENCE HOBBYIST website

billb at amasci com
http://amasci.com

EE/programmer/sci-exhibits amateur science,
hobby projects, sci fair

Seattle, WA 425-222-5066 unusual phenomena,
tesla coils, weird sci

=20


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Greetings,



You spoke about raising 2 balls and only 2 balls move out the =
other
side.



What if you pull back 3?



What if you pull back 4?



What if you pull one ball back on one side and one ball back on =
other
side?



What if you pull two balls back on one side and three on the =
other
side?



Repeat for all other possibilities.



In each condition there is a conservation of =
momentum.



What about the conservation of kinetic energy?



My first question is it an elastic or inelastic =
collision.



To answer that, pull one ball back and have one other ball at =
rest. (hold
the other three so they are out of the way).



My observation indicates that it is conserved or very nearly =
so.



Thus for both momentum (mv) and kinetic energy =
(1/2mv2) to
both be conserved, the after must be conserved.



If you have some old pool balls, make a larger apparatus out of =
them.
Or you could even use bowling balls of same mass.





Hope this helps



Dick





Helping teachers who facilitate, motivating =
students who
learn.

Dick Heckathorn 14665 Pawnee Trail
Middleburg Hts, OH 44130 440-826-0834

www.cvcaroyals.org/~rheckathorn/

Adjunct Physics Teacher - Baldwin Wallace =
College

Physics is learning how to communicate with ones environment so =
that it
will talk back.





-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On =
Behalf
Of William Beaty
Sent: Saturday, April 28, 2007 2:00 PM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Newton's Cradle



On Sat, 28 Apr 2007, Borislaw Bilash wrote:



> 1] When ball 1 & 2 are lifted and then relased =
why do
balls 4 & 5 rise

> up, rather than only ball 5 travelling at twice the =
speed?

>

> 2] why does ball 3 not move? (not the same =
question,
as 1)



Pretend that there are small gaps between all the balls. =
The
cradle still

works the same, which shows that all the collisions only involve =
two
balls

hitting each other, not two balls hitting a third. Drop =
one ball
in, and

it hits the next, which moves and hits the next, etc. Drop =
two

closely-spaced balls in and think about what should =
happen.



Or better yet, modify your actual Newton's Cradle so the balls =
are not

touching each other. Put 1mm gaps between. Then it =
goes
"zip zip zip"

rather than "clack clack clack."







(((((((((((((((((( ( ( ( (
(O) ) ) ) ) =
)))))))))))))))))))

William J.
Beaty &n=
bsp; &nb=
sp;
SCIENCE HOBBYIST website

billb at amasci
com &nbs=
p; =
;
http://amasci.com

EE/programmer/sci-exhibits amateur science, hobby =
projects,
sci fair

Seattle, WA 425-222-5066 unusual =
phenomena,
tesla coils, weird sci









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