## Abhisar one year ago If the potential energy of two molecules is given by $$\sf U=\frac{A}{r^{12}} - \frac{B}{r^6}$$then at equilibrium position, its potential energy is equal to

1. Abhisar

Answer given is $$\sf \frac{-B^2}{4A}$$

2. IrishBoy123

try this $\frac{dU}{dr}=\frac{-12A}{r^{13}}+\frac{6B}{r^7} = 0$ $r_e^6 = \frac{2A}{B}$ $U_e=\frac{A}{(\frac{2A}{B})^2}−\frac{B}{\frac{2A}{B}}$ etc

3. Abhisar

Thanks c: