1. The problem statement, all variables and given/known data Find the centroid of solid enclosed by surface z= y^2 , plane x=0 , x = 1 and z =1 . The density is 1 2. Relevant equations 3. The attempt at a solution Here's my working . Centoird = mass of inertia / mass So , i find the mass first . It's clear that the circle is on zx plane ... I am not sure whether to use z= rcos theta or z = rsin theta . Can you help ?