For the nth time, we were late this meeting because we had to finish the technical paper. Fortunately for us, though, the experiment this meeting was not really that demanding. We finished quite quickly and made up for the lost time brought about by us being late.
The goal of the experiment this meeting was to calculate the mass of a meterstick in a set-up wherein the meterstick was suspended from a height and was supported in its fulcrum point. We first had to determine the meterstick's center of mass (the point where mass is concentrated) by finding the right spot in its body wherein the meterstick, being suspended mid-air, was balanced. After that, we changed the fulcrum point and added weights to both sides, then carefully finding the positions of the weights that would balance the meterstick. We performed this part two times and took the average.
The mass of the meterstick could be calculated by equating all the torque (clockwise and counterclockwise) to 0, since the whole set-up is in equilibrium. The only missing term in the equation is the mass, and it could be derived with simple algebra.
Using an electronic balance, we measured the true mass of the meterstick. To our pleasant surprise, our calculated mass was only off by less than 1 percent.
After this, we were tasked to make the mass of the meterstick nonuniform - which was done by placing a weight on it- and then calculate the mass of the meterstick+weight by adding weights and by equating the torque with the aforementioned condition (torque=0). We only performed one trial because we were quite confident of our calculations. We, then used the balance to calculate mass, and once again, we were only off by less than 1 percent.
My friend and I made a promise that we would not be late next meeting. In turn, it was also a promise that we would not rush our technical paper and cram the night before.