PHYSICS PROBLEM SOLVING

(^)
Above the entrance door of an old German
"GASTHAUS" hangs a sign. A 200 N metal beer
mug hangs at the end of a 3 meter long strut that is
attached to the wall by a hinge. The weight of the strut is 100 N. A support cable is attached to the
strut at a point 2 meters from the wall and makes a
30
angle with the strut. Find all the forces acting
on the strut. Useful information: 0 F = 0 and 
=
GASTHAUS
Figure 2-1. AT THE GASTHAUS
Applying the Toulmin categories and argument structure to the At the Gasthaus
problem, an overall diagram of the solution can be visualized. This kind of visualization
helped me understand the types of statements students made as they solved the problem.
Figure 2-2 (page 53) shows the overall structure of this problem using the Toulmin
terminology.
The students are immediately presented with a picture and information. In a sense
they do not have to “decode” the problem and can start immediately with the Physics
Description. The data in the problem statement (e.g., 200 N, 3 m, etc.) constitute the
"Grounds" for the problem. Throughout the solution, students will refer back to the
problem statement for these grounds and will make either explicit or implicit references
to the grounds.
The "Warrants" in this problem are the same for other problems in statics, namely
that the sum of the forces and torques must be zero for equilibrium. A general warrant in
this problem is that both F = 0 and 
= 0 must be used. This general warrant has