Two identical spherical balls of mass $M$ and radius $R$ each are stuck on two ends of a rod of length $2R$ and mass $M$(see figure). The moment of inertia of the system about the axis passing perpendicularly through the centre of the rod is

A rigid massless rod of length $3l$ has two masses attached at each end as shown in the figure. The rod is pivoted at point $P$ on the horizontal axis. When released from the initial horizontal position, its instantaneous angular acceleration will be

Three particles of masses $50 \mathrm{g}$, $100\mathrm{ }\mathrm{g}$ and $150\mathrm{ }\mathrm{g}$ are placed at the vertices of an equilateral triangle of side $1 \mathrm{m}$ (as shown in the figure). The $\left(\mathrm{x},\mathrm{y}\right)$ coordinates of the centre of mass will be:

Seven identical circular planar disks, each of mass M and radius R are welded symmetrically as shown. The moment of inertia of the arrangement about the axis normal to the plane and passing through the point P is: