- Për përdorime të tjera, shikoni Teorema e Helmholcit.
Teorema e Helmholcit e mekanikës klasike pohon se :
Le të jetë
![{\displaystyle H(x,p;V)=K(p)+\varphi (x;V)}](https://wikimedia.org/api/rest_v1/media/math/render/svg/b24da9331e0f4924e90ab4ccc6812ff359a3a422)
funksioni Hamiltonian i një sistemi një-dimensional, ku
![{\displaystyle K={\frac {p^{2}}{2m}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/b29655ee557474de63d253ca16992585c130c56e)
është energjia kinetike dhe
![{\displaystyle \varphi (x;V)}](https://wikimedia.org/api/rest_v1/media/math/render/svg/2b5f9e167999d177cc82df1b6a007ec6d25493d7)
është një profil "në forme-U" i energjisë potenciale i cili varet tek parametri
.
Le
të tregojë mesataren kohore. Tani
![{\displaystyle E=K+\varphi ,}](https://wikimedia.org/api/rest_v1/media/math/render/svg/80f25fe7c01284b24f45afa871ccf0167812e0ff)
![{\displaystyle T=2\left\langle K\right\rangle _{t},}](https://wikimedia.org/api/rest_v1/media/math/render/svg/2944f7162213b8a03c255b9e720f08ff3d2ca068)
![{\displaystyle P=\left\langle -{\frac {\partial \varphi }{\partial V}}\right\rangle _{t},}](https://wikimedia.org/api/rest_v1/media/math/render/svg/8d5b7c1fbc262b3928f68afbad59e642ba47d410)
![{\displaystyle S(E,V)=\log \oint {\sqrt {2m\left(E-\varphi \left(x,V\right)\right)}}\,dx.}](https://wikimedia.org/api/rest_v1/media/math/render/svg/2752858325f9a4e28b7f6210579381b3e40ee228)
Pra siç shikohet:
![{\displaystyle dS={\frac {dE+PdV}{T}}.}](https://wikimedia.org/api/rest_v1/media/math/render/svg/6844c2d171273d029a7d51a49a9786d480dcba9d)