Applet shows the motion of the centre of mass of a dumbbel shaped object. The red and blue dots represent two masses and they are connected by a massless rod. The dumbbel's projection velocity can be varied by using the velocity and angle sliders. The mass ratio slider allows shifting of centre of mass. Here m1 is the mass of the blue object and m2 is the mass of red object. Check boxes in the view menu for path of blue body and path of red body can be used to display or turn off the paths of the two masses.