Mention the centre of mass of three particles which are not in line but have equal masses. 

What is centre of mass ?

A system consists of $3$  particles each of mass $m$ and located at $(1, 1), (2, 2), (3, 3)$. The co-ordinate of the centre of mass are

A circular disc of radius $R$ is removed from a bigger circular disc of radius $2R$ such that the circumferences of the discs coincide. The centre of mass of the new disc is $\frac{\alpha}{R}$ form the centre of the bigger disc. The value of a is $\alpha $ is

Three identical spheres, each of mass $1\ kg$ are placed touching each other with their centres on a straight line. Their centres are marked $K, L$ and $M$ respectively. The distance of centre of mass of the system from $K$ is

Find the center of mass $(x,y,z)$ of the following structure of four identical cubes if the length of each side of a cube is $1$ unit.