The way I see it,if there's a set up A which has 5 particles and another set up B which also has 5 particles,and assuming everything else is same in these set up,like distance between particles etc,if I increase the amplitude of particles in A set up,then that particle would go and push the 2nd particle,but,since it's amplitude has increased,it and the 2nd particle together will go and hit the 3rd particle(assuming the particle have enough amplitude to achieve this),similarly,now the 2nd and 3rd particle should do the same,so,since one particle is pushing 2 particles,this,should increase the speed compared to the set up B,so why doesn't this happen?