The document describes using a student's clenched fist as an analogy to explain the behavior of rubber bands when heated. Squeezing the fist tightly mimics heating a rubber band, as the forearm muscles activate similarly to how increased temperature causes disorder in rubber's polymer fibers. Upon releasing the fist, the muscles resist fully opening the hand, just as a cooled rubber band slowly returns to its original length, mimicking the behavior of rubber at ambient temperatures. The document suggests having students squeeze and then slowly open their fists to demonstrate these molecular-level processes in an accessible, hands-on way.

1. Rubber hand
An effective way of explaining molecular behaviour to students and the public alike is by
relatability and easily recognizable occurrences. Human body functions are relatable and
accessible.
In the case of rubber band retraction in the presence of increased temperature we have the hand
staying clenched, after being squeezed tightly for a few seconds, you have an example and
relatable occurrence.
By th students squeezing the hand the forearm muscle titin is activated by electrical impulses the
retention of the hand's position is the current line staying open. In an ideal rubber band as an
elastomer ( a bundle of disorganized copolymer fibers until stretched) the relation between
restoring force or retracting (f) , length φ (L), temperature (T) is linear as shown in the follow
equation
f= T φ (L)
Ask the students to squeeze their hands for a few seconds as shown in the picture below
The clenching mimics the the disorder of copolymer fibers in rubber when heated. After a few
seconds ask the students to open their hands as shown below
Their forearm
muscles will resists slowly

2. opening this mimics the cooling and slow return to ambient temperature of rubber.
Recap
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Hand clench is analog for retraction of rubber
Electrical impulse analog for heat that causes retraction
Opening of hand analog for rubber's return to ambient temperature