# q1_sol - ) and v y depends on sin( kx-ωt ), the latter...

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Quiz 1 Phys. 2306-94850 F09 You may use your text book, notes, and a calculator. A transverse wave on a string of mass/length μ is generated by Fxing one end of the string and attaching the other end to a motor that has an amplitude A, maintains a tension T and operates at frequency f. 1) If you want to reduce the wave length by a factor of 3.7 you can, a) keep μ and T unchanged, increase f by a factor of 3.7 b) keep f unchanged and lower both T and μ by a factor of 3.7 c) keep f and μ unchanged and lower T by a factor of 3.7 d) all of a-c e) none of a-c. Since v = λf = r T/μ , only choice (a) works. 2) A string particle has maximum kinetic energy when the displacement y a) = A b)= - A c) = 0 d) = A/ 3 . 7 e) = - A/3.7 A possible wave function is y ( x, t ) = A cos( kx - ωt ) Then v y = dy/dt = ωA sin( kx - ωt ). Since y depends on cos( kx - ωt

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Unformatted text preview: ) and v y depends on sin( kx-ωt ), the latter squared has maximum value when the former has value zero, (c). 3)A string particle has maximum acceleration in the y direction when y a) = A b)=-A c) = 0 d) = A/ √ 3 . 7 e) =-A/3.7 a = dv y /dt =-ω 2 A cos( kx-ωt ) =-ω 2 y So when y =-A , a has maximum value in the y direction, (b) 1 4) In order for the wave to deliver the same average power as you get from doubling A, you can keep A Fxed and a) increase f by a factor of √ 2 b) lower f by a factor of √ 2 c) increase f by a factor of 2 d) all of a-c e) none of a-c P ave = √ μT (2 πfA ) 2 / 2. So if you double A , P ave increases by a factor of 4. So you can get the same increase by keeping A Fxed and doubling f , (c). 2...
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## This note was uploaded on 12/24/2011 for the course PHYS 2306 taught by Professor Ykim during the Fall '06 term at Virginia Tech.

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q1_sol - ) and v y depends on sin( kx-ωt ), the latter...

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