5.4 Free Body Diagram Questions - Maple T.A. 2016 Help
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5.4 Free Body Diagram Questions


Free Body Diagram questions can be used to ask a student to draw forces from one or more starting points (called control points) over a background image.


Students are graded on their ability to correctly answer:

  1. The type of force
  1. The number of forces
  1. The control point or points
  1. The correct angle or angles

No partial marks are assigned, however, you can specify a question-wide tolerance on the angles. By default, this tolerance is five degrees. You can also customize how angles are matched on a per-force basis. For more details, see Customizing How Angles Are Matched.

Customizing how angles are matched

When comparing the angles of a student’s force and a correct answer force, Maple checks whether the angles agree to within the question-wide angle tolerance described above. This default behavior can be overridden for each force. There are three angle tolerance options available to each correct answer force. They are as follows:

  • default: specifies a question-wide tolerance on the angles, which is five degrees by default.
  • collinear: ensures that the student’s forces lie along the same line as the answer force, within the question-wide angle tolerance.
  • any: matches the name of any student force against the name of the answer force, regardless of angle.

The author specifies how angles are matched by:

1. Click Edit Source.

2. Complete the angleCriteria field by specifying default, collinear, or any.

For example, suppose the correct answer consists of three forces: a default angle matching for the first, collinear for the second, and any for the third. This would be specified as:

angleCriteria = ["default", "collinear", "any"]@

Alternatively, the instructor could supply their own Maple comparison procedure rather than saying collinear or any. This procedure must accept exactly three input arguments: two angle values in the range from 0 to 360, followed by a nonnegative tolerance value, and it must return either true (meaning that the angles are considered equivalent) or false. For example, the following procedure checks if two angles are in the same quadrant:

proc(a1, a2, tol) evalb(a1>=-tol and a2>=-tol and a1<=90+tol and a2<=90+tol or a1>=90-tol and a2>=90-tol and a1<=180+tol and a2<=180+tol or a1>=180-tol and a2>=180-tol and a1<=270+tol and a2<=270+tol or a1>=270-tol and a2>=270-tol); end proc

Maple will replace the third argument with the question’s angle tolerance value.


To create a Free Body Diagram question:

  1. From the Class Homepage, click Content Repository in the top menu.
  1. From the Create New drop-down menu, select Question/Text.
  1. This brings you to the Question Designer screen:

  • Enter a title for the question under the Question Name panel.
  • Enter the question in the Question Text.

  1. Click Response Area ().

5. Under the menu options Choose Question Type, select Free Body Diagram. The Edit Response Area window is shown in Figure 5.5.

6. Specify the Free Body Diagram as described in the section Define the Free Body Diagram below.

7. Click Save and then Preview to see the question.

Free Body Diagram Authoring

Figure 5.5: Free Body Diagram Authoring

Define the Free Body Diagram


Specify the weight of this question in the overall assignment.

Angle tolerance

Define the angle of tolerance (in degrees). When the question is graded, the acceptable answer is within a tolerance range of whatever is specified. The default is 5.0 degrees.

Background Image

This is mandatory. To upload a background image, click Choose File/Browse... to select an image from the Class File Manager.

Creating a subfolder
  1. Right-click on Files to create a subfolder.

2. Enter a name for the new folder and click OK.

3. Click Upload to load new images into the folder.

4. Double-click on the image to select it.

5. Scroll down to confirm that the image was added to the diagram.

Note: The drawing board is 600 by 450 pixels. If you upload a background image whose width exceeds 600 pixels or whose height exceeds 450 pixels, the image will be scaled down (aspect ratio preserved) to fit the drawing board.

Show instructions

Specify whether Maple T.A. should display its default introductory instructions for this tool to students, by choosing Yes (the default) or No from the drop-down menu.

Select forces

Use the check boxes to select the appropriate forces on the free body diagram.

To add a force that is not listed, define a new type of force by assigning it an abbreviation (Abbr.) and a force name (Name). Click Add force type to have the customized force added to the bottom of the list.

After you have finished adding forces, click Update force selection list below.

Add control points

Enter the Control Point Label and then click Add. Automatically, the control point will be added to your free body diagram. To move it, click the control point and drag it to its new location. After the control point label has been added, click Update Label to modify it or Delete to delete it. Multiple control points can be added to the free body diagram, from which multiple forces can be drawn.

Add a force

Select a force from the drop-down menu. A force can be selected multiple times. Assign an Angle (in degrees) and if applicable, a control point as its Origin, to each force and click to add the force to the free body diagram preview.

Note: Valid angles are between -180 and 360 degrees, inclusive. Half angles are accepted as well; for example, 100.5 degrees.

List of forces

All forces added to the diagram appear in a table at the bottom.

Selecting a force

To select a force, use one of the following methods:

  • Click the force in the diagram.
  • Click the force within the table.

Both options result in the force being highlighted blue. Also, a blue point, or handle, appears at the tip of the drawn force.

To change the angle of a selected force
  1. Drag its handle on the diagram. This approach also affects the arrow's length. This, however, has no impact on the grading since force magnitudes are not considered.
  1. Enter an angle (in degrees) on the table and press Enter.

To change the type of a selected force or to move that force to a different control point (if applicable), use the corresponding drop-down menus in the table row. To delete forces, click Delete.

See Also:


To view Free Body Diagram question examples:

  1. From the System Homepage, select the class called Maple T.A. Readiness Class.
  1. From the Assignments panel, click Free Body Diagram Questions, as shown in Figure 5.6 below.

Note: Alternatively, you can view Free Body Diagram questions individually through the Content Repository by selecting the group called Free Body Diagram Questions.

Free Body Diagram Questions in the Demonstration Class

Figure 5.6: Free Body Diagram Questions in the Demonstration Class

Next Steps

To edit further details in the Content Repository, see Editing Question Details.