NOTICE that the period does NOT depend on the mass that is swinging! So, check that out. Use TWO coffee cups and repeat. (Make sure the length does not change too much!) Describe what you did and what you conclude. As long as the amplitude (how far it swings back and forth) is not too big, the period T does not depend on how far it is swinging. Repeat the measurement A above for two amplitudes. What do you conclude