In figure 1 a point mass is tethered so as to move along a circular path. The connector has been highlighted so that it can be destroyed by pressing the Delete button on the keyboard. Figure 2 shows the situation just after the connector was destroyed. The mass is moving off along a tangent to the original circle.

Figure 3. Two objects, one of which contains an approximation of a non-point mass, are given identical shoves.

Figure 4. The object which consists only of point masses rotates through a larger angle than the one which contains a non-point mass.

So far we have only worked with point masses. This raises the question of how a mass which occupies an extended region of space will behave during a rotation.

The two objects in figure 3 are identical except that in one the lower mass is concentrated at a single point while in the other it is divided between two points in order to approximate a continuous mass spread over space. The structures have been given identical shoves.

Figure 4 shows the results after the simulation has run for a short time. While the centers of mass of the two objects have moved identically, the lower object has rotated farther than the upper one. Extended objects are more difficult to rotate than objects in which all the mass is concentrated at a point.