FBD: Equations from Sketch - mkraska/meclib GitHub Wiki

This is part of the FBD Example Question tutorial. We assume that you accomplished the parts

Now we want to display the sums of forces and moments about a point selected by the student. This is formative feedback. We put it in the Specific Feedback part of the Question, such that it can be suppressed in the quiz settings.

The sums serve as teachers answer in the later feedback for student-supplied equations of equillibrium.

image

Question text

**Gleichgewichtsbedingungen**

Wählen Sie mit dem blauen Fadenkreuz einen Bezugspunkt für das Momentengleichgewicht.

Specific Feedback

<p>Diese Gleichgewichtsbedingungen ergeben sich aus Ihrem Freischnitt.</p>
<p>[feedback:GGB](/mkraska/meclib/wiki/feedback:GGB)</p>

Press "Verify the question and update the form".

PRT GGB

See Sums of Forces and Moments for details of the function sums_xyM(). It actually extracts the sums out of the state variables of the sketch.

The index i_P points to the "crosshair" object. It's return value in the names input are the current coordinates.

  • Set PRT feedback style to "Formative".

Feedback variables

obj: stackjson_parse(objects);
GG: sum_xyM(obj,names,names[i_P],a);

Node 1

  • Set the test to "Algebraic" and set Tans to 1 and Sans to 1 (dummy test, always true).
  • Node 1 true feedback text:
<p>\( \displaystyle \Sigma F_x={@GG[1]@}\) </p>
<p>\( \displaystyle \Sigma F_y={@GG[2]@}\) </p>
<p>\( \displaystyle \Sigma M_\oplus={@GG[3]@}\) </p>

Check

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  • Fill in the correct response
  • Check