Question

Potential Energy in a field is given by U= - A/r⁶+ B/r¹¹ then find value of r for equilibrium position.​

Answer 1

WPE :

F = -dU/dx = 0 { for equilibrium posn }

11B/r¹² - 6A/r⁷ = 0

r⁵ = 11B/6A

r = ( 11B/6A )⅕

Answer 2

Given :- U = -A/r⁶ + B/r¹¹ (equiblirium position)

∵ F = - dU/dr

∴ dU/dr = d(-A/r⁶ + B/r¹¹) = 6A/r⁷ - 11B/r¹²

★ We know that for equiblirium position . F = 0

6A/r⁷ - 11B/r¹² = 0

6A/r⁷ = 11B/r¹²

r⁵ = (11B/6A)

r = (11B/6A)⅕ Answer