Materials: Cardboard (index card),Scissors, Nail, Ring Stand, Clamp, Thread, Paper Clip, Hole Puncher, Ruler.

How Is Center Of Gravity Found?

Procedure:

1. Cut a piece of cardboard into a shape similar to the one on this page.


2. Around the edge of the cardboard, punch 5 holes, evenly spaced. Number the holes 1-5.


3. Try to balance the cardboard flat on your fingertip.


4. Cut a piece of thread 30cm long


5. Tie the weight to one end of the thread and make a loop in the other end.


6. Set up a ring stand, clamp, and nail as shown.


7. Place the cardboard on the nail at hole 1.


8. Place the loop of the thread in front of the cardboard on the nail.


9. Make a dot where the thread hits the bottom of the cardboard.


10. Remove the thread and cardboard and use a ruler to draw a straight line from the dot to hole 1.


11. Repeat steps 7 through 10 using each of the four remaining holes.

Observations:
Describe the appearance of the lines on the card.

Conclusions

1. Where is the center of gravity of the index card?






2. Why is this point the center of gravity?






3. Try to balance the index card on the end of your finger. At what point does the object balance?




Why?





4. Could this method be used to determine the center of gravity of a regularly shaped object?

Critical Thinking:

1. A tightrope walker will fall if he leans too far over to one side. Relate this to the concept of center of gravity.









2. You cannot bend over and touch your toes if your heels are against the wall. Give this a try. Explain this in terms of center of gravity.

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