Replace 2nd part of list returned with function squared

Question

As mentioned above, I want to replace the 2nd part of a list returned from a function with the 2nd part squared.

n[s]:= {1*s,2*s};
ReplacePart[n[s],2->?^2]

I need the question mark to equal the current value returned. What is the most concise way of doing this with or without ReplacePart?

Answer 1

Perhaps

n[s]:= {1*s,2*s}; 
n[s]/.{y_,z_}->{y,z^2}

which returns {s,4s^2}

You can also write that as

ReplaceAll[n[s],{y_,z_}->{y,z^2}]

If the list may or may not have more than two elements then

ReplaceAll[n[s],{y_,z_,x___}->{y,z^2,x}]

will maintain any additional elements unchanged