# If I put an extra marble in a marble-filled-pipe how fast will one drop out on the other side (and is this different from pushing a stick)?

I thought I had found the answer to the question of how fast the other end of a stick will react if I push it (I thought after reading the answers and comments that the other side of the stick reacts conform to the speed of sound in the stick). But then I thought of this. A pipe is filled with marbles. I put an extra marble in on one side. When will a marble drop out on the other side? I can't imagine that the speed of sound is involved in this. Will not another marble drop out (almost) instantaneously? If the pipe is long enough and this would happen with the speed of sound, wouldn't the pipe be momentarily too short for all the marbles to fit? Is this different from pushing a stick?

• The speed of sound in solids is very fast (in metals $$\mathcal{O}(10^3m/s)$$... think about how large the object must be for this to have a noticeable effect). This is why we think in everyday life every push results in instantaneous movement of the whole object.