Calculating the speed of longitudinal wave

[bolzano95]

Homework Statement

I didn't quite understand my professor when he defined the speed of longitudinal wave.
Lets say I have a slinky and on one side we act with a force F along the slinky. Well, he said that this part then starts to move with velocity v.
But how? v isn't constant...

Homework Equations

The Attempt at a Solution

 

[berkeman]

I didn't quite understand my professor when he defined the speed of longitudinal wave.
Lets say I have a slinky and on one side we act with a force F along the slinky. Well, he said that this part then starts to move with velocity v.
But how? v isn't constant...

Have you seen animations or videos of this situation? As with transverse waves, the spring constant and the linear mass density enter into the equations, right?

Is your main question about the wavefront at the start of a wave packet, or do you have problems with the continuously propagating case too?

 

[bolzano95]

Of course! I totally get it now :)
I had a problem with the force and the velocity (constant force- velocity is changing). I realized because there is a force acting on the medium and therefore there is a change is momentum. And from this change of momentum you take the velocity, right?