View Proposal #177
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| ID | 177 |
|---|---|
| First Name | Kenneth |
| Last Name | Driessel |
| Institution | #non-IA section |
| Speaker Category | faculty |
| Title of Talk | The Dynamics of a Planar Two Link Chain and Some Applications to Human Motion |
| Abstract | Try the following 'acceleration experiment': Stand balanced with your legs straight and a slight forward bend at the waist. Then step backwards. Consider the following 'acceleration question': How do humans initiate this motion? Or more generally: How do humans usually initiate horizontal motion from a balanced position? (I first met this question when thinking about cross country skiing.) We analyze the acceleration question by analogy. In particular, we study the classical dynamics of a mechanical system consisting of two linked rods. We assume that the first rod is connected to the ground by a hinge. (The first rod corresponds to the human legs. The ground hinge corresponds to the human ankles.) We assume that the second rod is connected to the first one by another hinge. (The second rod corresponds to the human torso. The second hinge corresponds to the human hips.) We derive the equations of motion for this mechanical system. We prove that if the system is initially at rest in a balanced position then gravity causes the center of mass to accelerate in the horizontal direction toward which the system is 'pointed'. We infer that the step backwards in the acceleration experiment is initiated by a relaxation of the muscles at the hips. Reference: Kenneth R. Driessel and Irvin R. Hentzel, 'Dynamics of a Planar Two Link Chain', http://www.fiberpipe.net/~driessel/2-links.pdf |
| Subject area(s) | classical mechanics, bio-mechanics |
| Suitable for undergraduates? | Yes |
| Day Preference | |
| Computer Needed? | N |
| Bringing a laptop? | N |
| Overhead Needed? | Y |
| Software requests | |
| Special Needs | |
| Date Submitted | 4/3/2006 |
| Year | 2006 |