Find the Mass and Center of Mass of a Thin $x ^ { 2 } + y ^ { 2 } = r ^ { 2 }$

Essay

Find the mass and center of mass of a thin wire in the shape of a quarter-circle $x ^ { 2 } + y ^ { 2 } = r ^ { 2 }$ , $x \geq 0 , y \geq 0$ , if the density function is $\rho ( x , y ) = x + y$ .