Power of a transverse wave related to rope length

In summary, the power transmitted down the shorter rope is 1/4 of the power transmitted down the longer rope.
  • #1
symphwar
9
0

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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  • #2
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.
 
  • #3
Thanks so much! I was worried about missing something there.
 

Related to Power of a transverse wave related to rope length

1. What is the relationship between power and rope length in a transverse wave?

The power of a transverse wave is directly proportional to the length of the rope. This means that as the length of the rope increases, the power of the wave also increases.

2. How is the power of a transverse wave related to the amplitude?

The power of a transverse wave is directly proportional to the square of the amplitude. This means that as the amplitude increases, the power of the wave increases exponentially.

3. Can the power of a transverse wave be changed by adjusting the tension in the rope?

Yes, the power of a transverse wave can be changed by adjusting the tension in the rope. Increasing the tension will increase the power of the wave, while decreasing the tension will decrease the power.

4. Is the power of a transverse wave affected by the frequency of the wave?

Yes, the power of a transverse wave is directly proportional to the frequency of the wave. This means that as the frequency increases, the power of the wave also increases.

5. How does the power of a transverse wave change when the rope is doubled in length?

If the length of the rope is doubled, the power of the transverse wave will also double. This is because the power is directly proportional to the length of the rope, so doubling the length will result in a doubling of the power.

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