What is the definition of wave speed?

[ShudyShab]

Hi :) I just want to know how you would simply define the speed of a wave in words?
Because I often get questions asking to define the speed of a standing wave etc.

One of the definitions I know for progressive wave is the rate at which energy is transferred by a wave.

but what about the speed of a standing wave?

 

[SteamKing]

The speed of a standing wave is one which is stationary in position:
http://en.wikipedia.org/wiki/Standing_wave

 

[chrisbaird]

Speed can mean different things.

1. The speed of a simple sine wave is the distance that each peak of the sine curve shape travels in a given amount of time (phase velocity).

2. The speed of a wave packet is the distance that the peak of the wave packet's envelope curve travels in a given amount of time (group velocity). Energy travels at the group velocity.

3. In non-scientific usage, "speed" may also refer to the rate in time at which a fixed point in space waves on and off. In science, we call this the "frequency" of the wave, not the "speed".

So, a standing wave has a speed of zero, because the peaks do not travel, but has a non-zero frequency, because points are still waving on or off (or up or down for transverse waves). Take a look at my http://faculty.uml.edu/cbaird/95.658%282011%29/Lecture3.pdf" for a more rigorous explanation.

 

[ShudyShab]

Thank you :) I'll check out all the links

 

[Rockstar3143]

can't we define the speed of stationary wave as follows:-

Stationary wave is produced by the superposition of incident and reflected waves and the speed of stationary wave is the speed of anyone of the incident or reflected wav.

(As given in marking scheme of CIE).

 

[ShudyShab]

Thanx that's perfect! Its exactly what I need as I am writing CIE