Biomechanics is the branch of science that brings together two branches of knowledge that may seem to be quite different - biology and mechanical engineering.  Biomechanics takes the understanding of machines and motion that engineers have developed, and applies it to explain how living things move and work.

One branch of biomechanics focuses on the marriage of mechanical engineering and medicine in the design of artificial systems that replace human joints and limbs.  Another branch, called ergonomics, focuses on designing machines that are more compatible to the way humans move.

SUMMARY: This activity examines the similarities - and differences - between animal motion and mechanical motion.

GOAL: AT the conclusion of this activity, students should be able to discuss the similarities and differences between animal motion and mechanical motion in terms of energy inputs, work accomplished, and system designs.  They should also be able to identify the application of simple machine concepts in various biological designs.

ORGANIZATION: This activity can be completed individually, but you will probably want to have your students work in design teams to more closely simulate the real world of engineering.

TIME REQUIRED: One class period to complete the activity sheet; several periods ot research and completed the research assignment, if given.

SUGGESTED LESSON PLAN:

1. Organize your class into groups of three or four students each.  Distribute the "Biomechanics" student activity sheet.  Note: The sheet contains a section of questions and a research assignment.  You do not have to assign the research if time is short.
2. Introduce the concept that many mechanical systems of motion mimic biological ones.  Solicit examples (airplanes/birds; helicopters/bumblebees; submarines/dolphins; jet engines/squids). Note that none of the similarities is precise.
3. Discuss the fact that the same laws of physics apply to all motion, whether animate or inanimate.  The movement of any body requires energy.
4. Discuss the sources of energy for biological motion and mechanical motion (Biological: food; Mechanical: fuel). Review plant photosynthesis and digestion.  Discuss the carbon cycle.  Have students trace the energy flow in plants and animals.  Then have the students compare and contrast the biological energy flow to the energy flow in an automobile.  (Note: the basic source of energy for plants, animals and cars is the sun.)
5. Refer to the illustrations and questions on the student activity sheet.  Students are asked to identify the similarities and differences between biological and mechanical systems.  Make sure they understand that the similarities do not have to be exact.
6. Review the answer to the questions, making sure students are able to discuss each system's similarities and differences.
7. The optional research activity lets students find out more details of how different mechanical systems are designed after biological ones.  Their reports can be either written or oral.  All reports should also include a sketch or diagram that shows the systems' similarities and differences, as well as their basic designs.

An excellent resource on biomechanics is: Exploring Biomechanics: Animal Motion, by R. McNeill Alexander (Scientific American Press, 1992).