CM [015] Newton's Cradle

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NEWTON’S CRADLECM [015] The Motion of Phonons in


Newton’s Cradle

The transfer of phonons is best demonstrated by the setup named after Sir Isaac Newton - the Newton’s cradle.It is available in toy shops and stores associated with geographic and science societies. It contains several steel balls hanged on delicate wires or threads so that they can swing and hit each other straight.


One ball strike

In Newton's cradle five-ball system, one ball is pulled away and is left to fall; it strikes the first ball in the series and comes to nearly a dead stop. The momentum of the first ball disappears and reappears as the momentum of the last ball as it rises into the air.


Starting the motion


1st Ball drops to hit the 2nd ball


Phonons pass through the chain


Phonons lift up the last ball


The last ball drops back


The last ball starts the process again in the reversed way


The Passage of the Phonons


PASSAGE OF PHONON FROM ONE BOUND PARTICLE TO ANOTHER

The Mechanism of the


Free Particles

The is the scenario of one moving particle hitting another one which is at rest in free space.

The classical picture is like that of a particle moving and hitting a stationary one.

The phonon picture is slightly different in having a phonon mounted on the moving particle.

Classical picture. One particle moving toward another

Phonon picture. One compound moving towards another.

A B

A B


Sequences

1) Particle A moves close to particle B.

1) Particle B takes over phonon from particle A.

2) Particle B moves & oscillates; particle A being left motionless.


Bound particles in crystal lattice structure

In demonstrating the passage of photon from one particle to the other in matter, we use the simplest crystal lattice structure wherein the core particles are arranged in a perfectly orderly manner. Let’s begin with a group of particle elements space evenly in a single line, and let us assume that in the beginning, they don’t move at all. They interact with each other like there are springs between them.


Passage of phonons in Crystal Structures

The phonon drives the element closer to the next one and so is able to pass onto it. This goes on repeatedly until it reaches the last one.

1-D crystal structure

Phonon causes ion to vibrate and move closer to the next one.

Phonon passes over to the next one and repeats the process again.


THE PHONONThe end of discussions on the

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CM [015] Newton's Cradle