Speed of a wave problem

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In summary: Since you have the speed of the wave and the wavelength, you should be able to figure out the frequency.
  • #1
The figure shows a snapshot graph of a wave traveling to the right along a string at 45 m/s. Find velocity at 1, 2, and 3

I don't know how to approach this problem since I thought the speed of a wave traveled the same speed on all of the string but it tells me that 45m/s is wrong.
 

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  • #2
dtesselstrom said:
I don't know how to approach this problem since I thought the speed of a wave traveled the same speed on all of the string but it tells me that 45m/s is wrong.
I think they are asking for the vertical velocity of the matter point on the string... You have all the elements: you know the phase velocity and wavelength of the wave, and from the figure you can also read its amplitude (and phase). Write down the mathematical expression for the wave (hint: will be something like sin or cos of something), and then look at the motion of a point at fixed value of x...
 
  • #3
they have a equation that says Vy=-omega*Acos(kx-omega*t+phase constant)
I don't know what t or x stand for so how would I calculate this and isn't A at the point 0 equal to 0 therefore the velocity should be 0. I don't get how this equation is used and I can't find an example of it.
 
  • #4
dtesselstrom said:
I don't know what t or x stand for

:confused:
t stands for time, and x stands for the x-coordinate (along the wave motion) of course !
 
  • #5
I know what they stand for but I don't know what they are. How do I find these values? Also what do I do about A since it should be 0 at the point 0 so shouldn't the answer be 0. Everytime I try this equation I get the wrong answer.
 
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  • #6
Anyone have any more advice on this problem please.
 
  • #7
dtesselstrom said:
I know what they stand for but I don't know what they are. How do I find these values?
Since you have the speed of the wave and the wavelength, you should be able to figure out the frequency.

Also what do I do about A since it should be 0 at the point 0 so shouldn't the answer be 0.
A is the amplitude of the wave--it's not zero.
Everytime I try this equation I get the wrong answer.
You might need to review what the equation means; try reading http://hyperphysics.phy-astr.gsu.edu/hbase/waves/wavsol.html#c4"
 
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  • #8
Velocity of Points

I am trying to create the equation for the line like you said, i have solved values for A, f, w, and k. However, I cannot find the phase constant. Also, once I do have the equation, how it help me find the velocity at the different points?

Thanks in advance.
 
  • #9
How do you find t in this question?
 

What is the speed of a wave problem?

The speed of a wave problem refers to the calculation of the speed at which a wave travels through a medium.

How do you calculate the speed of a wave?

The speed of a wave can be calculated by dividing the distance traveled by the time it takes for the wave to travel that distance. This formula is represented as speed = distance/time.

What factors affect the speed of a wave?

The speed of a wave can be affected by the properties of the medium it is traveling through, such as density and elasticity. It can also be affected by the frequency and wavelength of the wave.

Can the speed of a wave change?

Yes, the speed of a wave can change depending on the medium it is traveling through. For example, sound waves travel faster through solids than through gases.

Why is the speed of a wave important?

The speed of a wave is important because it helps us understand how waves behave and interact with their surroundings. It also has practical applications, such as in the study of earthquakes and in communication technologies.

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