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How do we know that it is at x=0 that we get minimum potential energy; why not at x=1 or -1 where dU/dx is min.?

How do we know that it is at x=0 that we get minimum potential energy; why not at x=1 or -1 where dU/dx is min.?

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Grade:12

2 Answers

Parikshit Ranjeet Raje
13 Points
6 years ago
You may check the double derivative of U i.e. d2y/dxand put the values of x. If double derivative is -ve then it is a maxima and if +ve then its a minima.
V(x)= (x4/4) – (x2/2)
dV/dx= x3-x=0  
x=1,0,-1
d2V/dx= 3x2-1 (double derivative)
Put x=0,-1,1
d2V/dx2 at x=1,-1 is +ve
so minima at x=1,-1
Aishwarya Jee
13 Points
6 years ago
But the book says the min. Potential energy is 0, obtained at X=0, is there something to do with the negative sign of (-dU/dx)=F

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