Walter Lewin at MIT says that at a point of stable potential energy(like the troughs of a wavy surface), d^2u/dx^2 will be positive
And at a point of unstable potential energy(like the crests of a wavy surface), d^2u/dx^2 will be negative. Can someone give me some intuition and prove why this is true?
And at a point of unstable potential energy(like the crests of a wavy surface), d^2u/dx^2 will be negative. Can someone give me some intuition and prove why this is true?