Question

eight solid uniform cubes of edge l are stacked together to form a single cube with center o. one cube is removed from the system. distance of the centre of mass of remaining 7 cubes from o isa) 7√3l/16b) √3l/16c) √3l/14d) zero

Answer 1

choose x-y -z axes let centre of mass of 8 cube be O as origin
let the center of mass of each cube be (l/2,l/2.l/2)(l/2,-l/2.l/2)(l/2,l/2.-l/2)(l/2,-l/2.-l/2)(-l/2,-l/2.l/2)(-l/2,l/2.-l/2)(-l/2,-l/2.-l/2)and (-l/2,l/2.l/2)
there center of mass is (0,0,0)
if any one cube is removed then the center of mass can be
then only 7 cubes should be there
so as centers are at length l/2 the distance according to given choice
must be c)