PHYS 17200 Lecture Notes - Lecture 12: Diatomic Molecule
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PHYS 17200 - Modern Mechanics - Lecture 12_Internal Energy
● The vibrating diatomic molecule we’ve been considering consists of identical
atoms that move in opposite directions so that the molecule’s total momentum is
● Since its momentum is zero, there is a sense in which the molecule “at rest”.
However, it still has kinetic energy except when the atoms are at their greatest
and smallest separations.
● What we call the molecule’s vibrational energy is fundamentally the sum of this
internal kinetic energy and its potential energy.
● Similarly, what we call the thermal energy of a solid is the random vibrational
energy of its molecules and, so, fundamentally internal kinetic and potential
● An object of a larger mass will have greater energy than an object of a smaller