Two masses m1 and m2 are connected by by spring of spring constant k. If two forces F1 and F2 acts on the two masses respectively in mutually opposite direction (i.e. outwards) what would be the extension in the spring and the acceleration of the two masses. I think that if assuming F1>F2 then the extension in spring should be equal to x= F2/k and the forces acting on m1 would be F1 in forward and kx(F2) in backward direction. and on m2 F2 in backward and kx(F2) in forward direction. Where am I wrong in my assumption?