Blog 8-Seesaws

After a swim meet at Punahou, some of my friends and I went to play on the playground.  One of the fun things to play on at Punahou's playground are the seesaws.  Instead of rocking back and forth on them, as all the other children were doing, we, being physics/AP physics students, tried to balance the seesaws.

At first, we tried with only two people on the seesaw.  In this picture, Kevin and I are on the seesaws.  Since our weights are about 30 pounds different, he had to sit much closer to the fulcrum than I did.  By doing this, we were able to balance the torques on both sides of the seesaw.  If we were in a classroom, we would have been able to use the equation: TORQUE(ccw)=TORQUE(cw).  Since torque=force x radius, we could have set up the following equation: (106 N)x(2.5 m)=(135 N)x(r).  Kevin had to shift his center of mass to 1.9 meters away from the fulcrum in order for the seesaw to be balanced.

After we balanced the seesaw with two people, my other friend jumped onto my side of the board.  This time, Kevin had to shift his center of mass backwards in order to balance the board. Again, if we were in a classroom, we could determine the different torques on each side of the board: Fr + Fr=Fr.  Thus, (106 x 2.5) + (95 x .15) = (135 x r).  In this case, Kevin's center of mass is at 2.06 meters.