1. The problem statement, all variables and given/known data in my book , it stated that first moment is moment of mass , second moment as moment of inertia , is it correct ? 2. Relevant equations 3. The attempt at a solution IMO , first moment can also be called as first moment of inertia , with formula of Ix or Iy , whereas for second moment of inertia , it has formula of Ixx or Iyy.