Finding Your Center of Gravity

Purpose: To find your center of gravity

Materials

• 2 bathroom scales
• 2 rulers
• tape measure
• 1 board (long enough for you to lie on and strong enough to support your weight without bending)
• pencil

Procedure

1. With a partner, place two bathroom scales on a smooth, flat surface.
2. Weigh yourself on each scale to make sure that you weigh the same on each. If one scale reads a different weight, adjust the scales to match.
3. Lay a ruler vertically across each scale and place the board on top of the rulers. See diagram 1.

4. Determine the weight of the board by reading the scales and recording the sum of the readings on the chart below.
5. Determine the length of the board by measuring the distance between the rulers and recording this value on the chart below.
6. Lie on the board so that your feet are just above the ruler on the right scale, your head is just above the ruler on the left scale, and your arms are by your sides. See diagram 2.

7. Have your partner read both scales and record their readings on the chart below.
8. Stand against a wall and have your partner measure your height. Record on the chart below.
9. To find your center of gravity, follow the equation below the chart.

Key Terms: RS (Right Scale), LS (Left Scale), LBS (Length Between Scales), CG (Center of Gravity)

Partner Names	Weight of Board (RS + LS)	Length of Board in inches (LBS)	Right Scale (RS)	Left Scale (LS)	Your Height in inches	CG

	  Step 1

	  Subtract 1/2 the weight of the board from each recorded

	  value to find the new value.

	  RS - 1/2 weight of board = _________  New RS

	  LS - 1/2 weight of board = _________  New LS



	  Step 2

	  __________ X __________ = ____________

		 LBS		 New LS



	  Step 3

	  __________ + __________ = ___________

		New LS		New RS



	  Step 4

	  ___________________ ÷  _______________  =  ____________

	  Product from Step 2	Sum from Step 3		 CG

10. Using the value that you calculated above for CG, measure in inches the distance from your toes to find your center of gravity.

Conclusion

• Was the center of gravity the same for both you and your partner? Why or why not?

What's Happening?
The gravitational force that we call weight pulls down on each particle of an object. Although individual particles throughout an object all contribute to weight in this way, the net effect is as if the total weight of the object were concentrated in a single point--the object's center of gravity.