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Physics Problem Wire stretched with tension F. Transverse traveling waves of amplitude A, wavelength λ1 carry average power Pav1 = 0.700 W .?

A light wire is tightly stretched with tension F. Transverse traveling waves of amplitude A and wavelength λ1 carry average powerPav,1 = 0.700 W .

If the wavelength of the waves is doubled, so λ2 = 2λ1 while the tension F and amplitude A are not altered, what then is the average power Pav,2 carried by the waves?

Been stuck on this problem for quite some time and I m not sure where to start. Any help is appreciated.

Thank you in advanced

1 Answer

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  • ?
    Lv 7
    3 years ago
    Favorite Answer

    The speed (v) depends on the linear density (μ) and tension (F).

    v = √(F/μ)

    Since F and μ are unchanged v is unchanged.

    Using the link, the formula for transmitted power is:

    P = ½μω²A²v (see http://hyperphysics.phy-astr.gsu.edu/hbase/Waves/p... )

    Since μ, A (amplitude) and v are unchanged, P is proportional to ω²

    ______________

    ω = 2πf and f = v/λ so ω = 2πv/λ

    Since v doesn’t change ω is inversely proportional to λ.

    λ is doubled, so ω is halved. ω² is quartered.

    Pav2 = ¼Pav1 = 0.700/4 = 0.175W

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