The Physics of Rubber Bands What do rubber
The Physics of Rubber Bands
What do rubber bands and springs have in common?
What do rubber bands and springs have in common? • Exert a restoring force proportional to the displacement from equilibrium
D How are they different?
How are they different? • Rubber breaks cleanly
How are they different? • Rubber breaks cleanly • Spring-like nature not destroyed by overextension
D How are they different? • Rubber breaks cleanly • Spring-like nature not destroyed by overextension • Temperature changes with extension/relaxation
Why does rubber behave as it does?
Why does rubber behave as it does?
S Why does rubber behave as it does?
Other examples of random motion
Other examples of random motion • Scent expanding in air (gaseous mixture)
Other examples of random motion • Scent expanding in air (gaseous mixture) • Food coloring expanding in water (aqueous mixture)
Characteristics of random motion
D Characteristics of random motion • Random motion will lead to the most probable state
D Characteristics of random motion • Random motion will lead to the most probable state • The rate of random motion is temperature dependent
Why does rubber warm when stretched and cool when relaxed?
Why does rubber warm when stretched and cool when relaxed? • When rubber is relaxed it has lots of internal freedom
Why does rubber warm when stretched and cool when relaxed? • When rubber is stretched it has limited internal freedom
Why does rubber warm when stretched and cool when relaxed? • Stretching a rubber band restricts the random rotations
Why does rubber warm when stretched and cool when relaxed? • Stretching a rubber band restricts the random rotations • The energy that was involved in the random rotations gets converted into random vibrations and the band heats up
Why does rubber warm when stretched and cool when relaxed? • Conversely, it takes energy to start the random rotations when a stretched band is released
Why does rubber warm when stretched and cool when relaxed? • Conversely, it takes energy to start the random rotations when a stretched band is released • The energy for the random rotations comes from the vibrational energy of the band cools off
Why does rubber warm when stretched and cool when relaxed? • Energy is conserved
How might this property be useful?
How might this property be useful? • Refrigeration
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