Mass of a Meter Stick

My original plan for solving this challenge problem worked, however, it was much more complicated than it needed to be. We decided we would just come up with a plan along the way. Naeem and I constructed a seesaw instead of a countertop like the rest of the class. We rested the meter stick on a book with the weight on one end and balanced the stick so that it appeared horizontal. When doing this it was apparent that the side with the weight on it had a larger lever arm than the side with the other weight. This is when we took the formulas about torque and put them to use. The original formulas used:

 t=t

t=force X leverarm

force X leverarm= force X leverarm

w=mg

clockwise torque= counter clockwise torque

After taking measurements we knew that the meter stick was 100cm. The side with the weight had a lever arm of 28cm and the side with the meter stick balanced on it had a lever arm of 22cm. We also knew that the side with weight had a force of 98. This is because the force on it was the force of gravity and converting that to Newton’s it would be 98.

            28 X 98= 22 X F

            2744=22F

            F=124.727N

The force of this really wasn’t far off yet this process became a lot more complicated than it needed to be when the see-saw was made. So, we followed the common method used by the class even though we got similar answers either way. In the correct process we balanced the stick and the mass off a tabletop. It took out the variable of the extra meter stick and we also got different numbers. However the lever arms ended up in the same proportion (the side with the weight had a larger lever arm than the other side). Another thing that changed in this were the decimal points. We realized that last time we had moved the decimal points of the force of gravity had been moved to the right instead of the right so it actually should have been .98 rather than 98.

            20 X .98= 30 X F

            19.6=30F

            F=.653N

            .653=9.8m(w=mg)

            m=.06663g

            Answer:66.6g