OBJECTIVE: To demonstrate the influence of weight distribution on CG location and balance point.

DIRECTIONS: Attach weight to one end of string and put pin through a knot in the other end. Put the pin through the edge of one of the single thickness pieces of cardboard. Hold the pin only and allow the card and plumb line to swing freely. Draw a line on the card along the string. Repeat with pin in two other places on the card. Repeat with other cards.

1. What happened to the three lines?

2. Why?

3. What do the three lines represent?

4. What is the intersection of the lines?

5. Compare the results when a similar shaped card but with different weight distribution is used.

Put a large dot at the point of you best estimate of CG position in each of the shaped above.

6. Attempt to balance the cards on these intersection points. Do they balance?

7. Why?

8. Compare the various shaped cards and their balance points. Comment on the position of the balance points and the influence of the weighted parts on the location of the balance points.

McCarthy, J. (1979). Biomechanics Laboratory Exercises and Workbook. 2nd Ed. Minneapolis, Minnesota: Burgess Publishing Co.