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Unformatted text preview: khounvivongsy (sk27799) Homework 21 Weathers (17104) 1 This printout should have 13 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points Transverse waves with a speed of 53 . 5 m / s are to be produced in a taut string. A 6 . 66 m length of string with a total mass of 0 . 061 kg is used. What is the required tension? Correct answer: 26 . 2158 N. Explanation: Let : v = 53 . 5 m / s , L = 6 . 66 m , and m = 0 . 061 kg . The mass per unit length of the string is = m L , and the tension on the string is T = v 2 = mv 2 L = . 061 kg (53 . 5 m / s) 2 6 . 66 m = 26 . 2158 N . keywords: 002 10.0 points A light string of mass per unit length 12 . 3 g / m has its ends tied to two walls separated by a distance equal to three fourths the length L of the string as shown in the figure. A mass m is suspended from the center of the string, applying a tension in the string. 3 L 4 mg L 2 L 2 What size mass should be suspended from the string to produce a wave speed of 77 . 8 m / s? The acceleration of gravity is 9 . 8 m / s 2 . Correct answer: 10 . 0498 kg. Explanation: Let : = 12 . 3 g / m = 0 . 0123 kg / m , v = 77 . 8 m / s , and g = 9 . 8 m / s 2 . From the free body analysis of the vertical forces, we have mg = 2 T sin , so T = mg 2 sin . (1) The angle can be found from cos = 3 L 8 L 2 = 0 . 75 , so = arccos(0 . 75) = 41 . 4096 . Using Eq. 1, the wave speed is v = radicalBigg T = radicalbigg mg 2 sin m = 2 v 2 sin g = 2 (77 . 8 m / s) 2 (0 . 0123 kg / m) sin 41 . 4096 9 . 8 m / s 2 = 10 . 0498 kg . keywords: 003 10.0 points It is found that a 6 m segment of a long string contains 3 complete wavelengths and khounvivongsy (sk27799) Homework 21 Weathers (17104) 2 has a mass of 170 g. At one point it is vibrat ing sinusoidally with a frequency of 48 Hz and a peak to valley displacement of 0 . 34 m. What power is being transmitted along the string?...
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 Spring '09
 weathers
 mechanics, Work

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