Derivative chain rule clarification

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In a question, I am trying to find the first degree derivative of a vector

$r(t)= t^2\,\hat\imath - 2\cos\pi\,\hat\jmath$

Is this answer correct ?

answer : $r'(t) = 2t \,\hat\imath + 0 \,\hat\jmath$

I mean there is no t term in j vector,so shouldn't it be 0