Power of a transverse wave related to rope length

AI Thread Summary
The discussion focuses on the power transmitted by two transverse waves traveling down ropes of different lengths but with identical linear mass density, tension, and amplitude. It concludes that the power transmitted does not depend on the length of the rope, leading to the assertion that the power in the longer rope remains equal to that of the shorter rope, P = P0. The participants explore the relationship between phase speed, tension, and angular frequency, emphasizing that the angular frequency is likely the same for both ropes if generated by the same oscillator. Ultimately, the consensus is that the length of the rope does not affect the power transmitted. This reinforces the understanding that power in wave mechanics is influenced more by the medium's properties and the oscillator's parameters than by the rope's length.
symphwar
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Homework Statement


Two traveling transverse waves propagate
down two long ropes under the conditions
that the linear mass density, tension, and
transverse displacement amplitude for the two
ropes are the same, but that one rope has
twice the length of the other.
If the shorter rope has a power P0 being
transmitted along its length, then what is the
power, P, being transmitted down the longer
rope?
1. P = 1/4 P0
2. P = 4 P0
3. P = 1/2 P0
4. P = 2 P0
5. P = P0

Homework Equations


P = 1/2 uvA2w2
(u = linear mass density, w = angular frequency, v = phase speed)
v = sqrt(T/u)
(T = tension)

v = w/k
(k = wavenumber = 2pi/wavelength)

The Attempt at a Solution


Given that phase speed is related to tension and linear mass density, I think the values of u, A, and v are the same for both ropes. The only variable remaining is w, and I can't seem to infer what its value might be with the stated information.
Trying to find a relation with w and the given information, I realize I also do not know k or wavelength.
My understanding of a wave's power is that, with a given medium, w is controlled by the person/oscillator generating the wave. Could it be that it is implied w is the same for both waves, so that P = P0?
 
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I think you have the correct answer. The wave traveling down the rope could have any arbitrary value for w, (which would depend on how quickly the person/oscillator moved the rope up and down). So maybe you were supposed to assume the same oscillator was used for both ropes, so w is the same for both, so the power is the same.

In any case, you are right that the power transmitted doesn't depend on the length of the rope.
 
Thanks so much! I was worried about missing something there.
 
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