ASSIGNMENT 2Physics 218Due Feb 8Spring 2008Reading: Pain Ch 4-5.1. A musician finds that a string on her instrument oscillates at a frequency of 435 Hz instead ofthe desired 440 Hz (A). She adjusts the knob at the end of the string to bring it in tune.(a) Should she increase or decrease the tension in the string to bring it in tune?(b) What is the ratio of the correct tensionτcto the initial incorrect tensionτi?2. Pianos have steel strings about 1 mm in diameter for middle C (261.6 Hz). The density of pianowire isρ= 8 g/cm3and the maximum stress (force per unit area) that the wire can standwithout breaking is aboutS= 8×108N/m2.(Use this value for the maximum safe stress,although individual samples of wire will break at different stresses.)(a) What should the lengthLof the string be if the frequency is to be 261.6 Hz?(b) How does the tension in the string compare with the weight of a 150 lb person?(c) The keys on a piano range from a low A at 27.5 Hz to a high C at 4186 Hz. If all strings
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