Equation of motion for a particle with inverse and linear restoring forces

[rsaad]

Hi! I have attached the picture. Can someone please tell me what equation of motion will be?
My guess is that it will be

$\ddot{x}$ = -k/x -kx/2

 

[mfb]

What is x? What is "O"? What is fixed, what is not?
Those things labelled "k" are springs?
I don't think your answer is correct.

 

[Chestermiller]

Note that the springs are pulling in opposite directions. Check your signs.

 

[mfb]

I think the signs are right, but it depends on the (unknown) original problem. However, an x in the denominator looks odd and I would expect to see a mass in the equation.