# Can constant velocities produce a longitudinal wave?

1. Dec 19, 2009

### luckis11

At the simulators:
http://wildcat.phys.northwestern.edu/vpl/waves/wavetypes.html
http://www.ngsir.netfirms.com/englishhtm/Lwave.htm [Broken]

The velocity of each particle between two successive collisions is obviously not constant and it is defined by harmonic oscillation equations.

What a wavefront is (in this case of many particles moving and "colliding" according to harmonic oscillations), is the where a close distance between the particles is, as seen at every frozen frame of the movie. And there is a gradual increase of this distance as we are departing from the wavefront.

My question is, suppose every particle is moving with constant velocity between each change of its direction, and each change of its direction means a collision by contact with another particle. In this case, can it be produced a trevelling wavefront which will again mean "the where a close distance between the particles is, as seen at every frozen frame of the movie. And there is a gradual increase of this distance as we are departing from the wavefront"?

Last edited by a moderator: May 4, 2017
2. Dec 19, 2009

### Pythagorean

A particle changing direction can't have constant velocity. It has to slow down to 0 (accelerating from 0 to V or V to 0 instantaneously would require an infinite force); then it has to speed back up in the opposite direction.

3. Dec 20, 2009

### luckis11

Re: Can constant (between 2 collisions) velocities produce a longitudinal wave?

http://www.surendranath.org/Applets/Waves/Lwave01/Lwave01Applet.html [Broken]
At the above simulator, the velocity of each particle between two successive collisions seems constant, but I guess its't not, as it is harmonic oscillation motion:
http://wildcat.phys.northwestern.edu/vpl/waves/wavetypes.html

So anybody knows who can answer my initial question? I tried to contant the programmers of these simutators but they are not responding.

Last edited by a moderator: May 4, 2017