This is a simple applet that simulates an experimental setup that illustrates equilibrium of three forces. The forces are tensions in strings over pulleys supporting masses. The masses are adjustable within certain bounds.
Type of Material:
Java applet simulation
Recommended Uses:
Student practice of computations of two-dimensional, three-force equilibrium problems.
Technical Requirements:
Java enabled browser.
Identify Major Learning Goals:
To help students learn vector addition of forces and the condition for static equilibrium of a particle.
Target Student Population:
High School; Introductory College
Prerequisite Knowledge or Skills:
Trigonometry; Vector Components
Content Quality
Rating:
Strengths:
This applet is very simple to operate. It is a Realistic simulation of a possible lab setup. There is a good use of color coded force vectors.
The attachment point of the pulleys to their supports can be moved, allowing the student to observe that this does not alter the equilibrium conditions or the angles at which equilibrium constrains the forces to be applied.
Concerns:
This applet has limited applicability. The fact that the angles are measured from vertical may cause some initial confusion for students. Showing the angles (as when the "Parallelogram of Forces" box is checked) would be helpful.
It is possible to choose forces that satisfy the advertised constraints, e.g. (8,3,6), with a solution, yet the applet fails to compute the result.
Only integer values of weights are allowed, which limits the usefulness of the applet.
Potential Effectiveness as a Teaching Tool
Rating:
Strengths:
This simple situation should enable students to make calculations to check the results. The ability to move the pulleys and supports and see that the forces don't change could be surprising to students.
Concerns:
Requiring that students calculate at least one unknown (preferably two) would likely insure that they learn something. As is, it is too easy for students to just observe without thinking.
There is little to do in this applet. The applet would serve best as part of a carefully written assignment. However, since all answers are given, it would be difficult to create an effective assignment.
Ease of Use for Both Students and Faculty
Rating:
Strengths:
The applet is very easy to use, with few controls.
Concerns:
Changing force values is a little awkward. Dragging weights onto and off holders would likely give students a better realization of the forces involved.
The problem of the validity of some of the input parameters needs to be addressed.
Because all answers are immediately displayed,
it will be difficult for faculty to use the applet in an assignment or in-class exercise.
Creative Commons:
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