A pulley is 1.8 meters away from the wall. A 4 meter string that has a mass of 25 grams has one end attached to the wall and the other end hung over the pulley. A iron mass is hung from the end of the string hanging off the pulley. When plucked, it produces a fundamental frequency of 2000 Hz. What is the mass of the iron? Take this mass and experiment to the moon and find its 1st overtone and 3rd harmonic. The answers must use the units kg or Hz.