I didn't know that 3k was for a three-dimensional system. If that's the case, then how about trying 1k since this is a one-dimensional system.
Ok. I got the answer. The answer is 1k= 1.3807e23.
Thanks for joining the discussion, phys2211. And Thanks a lot for that important point you gave out.
Homework Statement
The diagram below shows a one-dimensional row of 5 microscopic objects each of mass 410-26 kg, connected by forces that can be modeled by springs of stiffness 26 N/m (so each object can be modeled as if it were connected to a single spring of effective stiffness 4ks = 104 N/m...