Pin Me

Two Methods to Determine an Object's Center of Gravity

written by: kellylynnmarie • edited by: Kellie Hayden • updated: 2/16/2013

Find out what center of gravity is and how it works. Then, put it to the test yourself with a center of gravity experiment. Between two easy, hands-on experiments using standard household items, you can determine the center of gravity of any object, regular or irregularly shaped.

  • slide 1 of 5

    What Is It?

    Center of Gravity is the point on an object at which all weight is concentrated. As described by NASA's Glenn Research Center, the center of Pencil Center of Gravity gravity is "the average location of the weight of the object." The motion of a particular object is usually due to the shifting and changing of the center of gravity, or center of mass. For the most, determining the center of gravity of an object does not seem necessary. However, for any flying object, it is extremely important to know the center of gravity in relation to all other parts of the object in order to determine or predict how the object is going to move or react to certain situations.

  • slide 2 of 5

    Center of Gravity Experiment #1 - Use Balance

    During the first experiment to determine the center of gravity, you are asking where the center of gravity is located and using balance to find it.

    Materials:

    • Carrot
    • Two forks
    • Drinking glass
    • Pencil

    Procedure:

    1. Insert the forks into the carrot on opposite sides to that the forks each stick out away from the carrot.
    2. Balance the carrot on the edge of the drinking glass.
    3. Describe how it is balancing and draw a picture of what you are seeing. Point out the center of gravity or where the weight needs to be centered in order to create balance.
    4. Now, remove the forks from the carrot and position them so both stick out facing down, below the carrot.
    5. Balance the carrot on the tip of the pencil.
    6. Describe how it is balancing and draw a picture of what you are seeing. Point out the center of gravity or where the weight needs to be centered in order to create balance.

    Conclusion: Explain what you learned when trying to find the center of gravity of an object.

  • slide 3 of 5

    Center of Gravity Experiment #2 - Find Plumb Lines

    In the second center of gravity experiment, you will find out how the principle learned could help a tightrope walker make it across.

    Materials:

    • Cardboard
    • Strong weight (a washer or bolt works great)
    • Hole punch
    • Nail
    • Pencil

    Prodedure:

    1. Cut the cardboard into a strange shape. Do not use a circle, square, rectangle, or any other common geometric shape.
    2. Punch a hole near the edge of the cut-out cardboard piece and hang it from a nail.
    3. Place the weight, a washer or bolt, on a thread and tie it off.
    4. Hang the thread and weight from the nail in front of the cardboard.
    5. Use a pencil to draw a plumb line down the cardboard where the thread touches. This marks your center line from that hanging point.
    6. Repeat step 2 and 5 in two other places on the cardboard.
    7. Remove the cardboard from the nail and balance on the tip of the pencil. You should know where to balance because it will be where all of the pencil plumb lines intersect, finding the center for you.

    Conclusion: Describe how you found the center of gravity and how this concept could help a tightrope walker make it across to his destination.

  • slide 4 of 5

    What Have Your Learned?

    From both experiments, you now understand that the center of gravity is found usually in one of two ways: The first is that an object will balance when the center of gravity is below the point where the object pivots. The second is that for irregularly shaped objects, the object will balance at the center of gravity, or the point where all of the plumb lines intersect.

  • slide 5 of 5

    References

    For more information on center of gravity, be sure to check out NASA's research and the Military Review on center of gravity.

    NASA Glenn Research Center: Center of Gravity Information

    Military Review: Center of Gravity Analysis