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Grade 11IIT JEE Entrance Exam

The potential energy of a particle in a certain field has the formU =a/r²-b/r,where A and B are positive constants, r is the distance from the centre of the field. the value of r0 corresponding to the equilibrium position of the particle (state if it is stable or unstable )is

Profile image of Sudhanva G V
7 Years agoGrade 11
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1 Answer

Profile image of Arun
7 Years ago
for equilibrium dU/ dr = 0
-2A/r³ + B/r² = 0 r = 2A / B
for stable equilibrium d²U /dr² should be positive for the value of r.
here d²U / dr² = 6A/r⁴ – 2B/r³ is +ve value for r = 2A / B So.