Real life science questions.

Interesting question.

I guess it would be an example of a periodic wave. Periodic waves vibrate up and down at a particular frequency. It would be possible to work out the speed of the wave but it would not be constant. You could possibly work out an average speed.

People with their hands in the air create a peak and the person next to them with their hands down give the illusion of a trough. The signal to raise your hand is when the person next to you raises theirs. By the time you raise your hand they have put theirs down.

Periodic waves are characterized by oscillating about their equilibrium position. In other words the people in the crowd stay in the one position. This is not true of all waves but it is true of periodic waves.

Tut