PHYSICS PROBLEM SOLVING

(^) One reason this group produced a fairly acceptable solution to this problem was
because they interacted very well as a group and despite the lack of physics knowledge,
and the previously mentioned error, managed to get several portions of the problem
correct. The section of dialog in Table 3-14 (page 99) illustrates their attention to the
details of the physics description. The difficulty with this diagram, of course, is that the
tension, normal force and weights of the mug and strut do not act all at the same place as
they have drawn it. In their “Plan”, they thus made a error when applying  = 0, and as
has been noted, use a moment arm of 2 meters instead of 1.5 meters. Even so, there is a
good use of warrants to support their argument. Their fatal error was the perpetual
problem with novice problem solvers: an improperly drawn free-body diagram! Later,
they drew an incorrect force-vector diagram because of this error in the free-body
diagram. The cluttered nature of the force-vector diagram is very evident in the sketch
opposite line 93 in Table 3-14.