1J10.09 - Center of Mass Demo

Code Number:
Demo Title:
Center of Mass Demo
Center of Mass
Area of Study:
Negatively Curved Block, Foam Ball with Offset Center of Mass, Bowling Pin, Claw Hammer, Offset Milk Stool Apparatus with 50 Gram Weight, Styrofoam Cup, 2 Golf Balls, Binary System, and Magnetic Marbles.

Balance the ball on the negatively curved surface. The foam ball has an offset center of mass which can be balanced on the curve when that mass is toward the bottom of the ball. The Guac ball is a blow up version of the foam ball and a round version of the larger Bozo demo.

The bowling pin or the hammer can be thrown in the air in a rotational motion and you should be able to see the spot in which they rotate. This also holds true for the binary system.

The milk stool is just barely balanced and will tip with an addition to just a small weight on the long end.

Place the two golf balls in the Styrofoam cup so that one golf ball is setting higher than the other, but is off center. Hold the cup at a height of 4 feet and drop. The cup should tilt so that the golf balls would hit the ground simultaneously if they weren't enclosed by the cup.

Roll the magnetic marbles together at a tangential angle. They should rotate at the center of mass.

The ball and the disks with the off-center centers of mass can be shown dramatically by placing them on the incline and watching them roll up hill a short way.

Note: This small binary apparatus is kept in the 1J10.09 "Center of Mass Demos" box.  The small binary apparatus is designed to be used with the Cenco Rotator Unit.  Secure the apparatus in the chuck of the unit and slowly increase the rotation rate until a center of mass of the system is observed.

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Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.