As mentioned, the results of problems like those shown in
Fig. 1 inspired the development of a tutorial that we refer to
here as the “first edition” version. This tutorial begins with an
experiment in which a ruler is supported on a smooth, horizontal
nail that passes through a hole in its center. The ruler is
held at an angle (see Fig. 4) and students are asked to predict
its motion after it is released from rest. An instructor then