Mechanics of gelation distinction between a sol (solution) and a gel therefore appears to be understood in a manner analogous to the practical distinction between the elastic and plastic deformation ranges of a metal. The distinction lies in the ability to respond to an applied shear force via macroscopic viscous flow. In a dynamic sense, the response of a gel to an alternating force (oscillation or vibration) will depend upon the period or frequency of vibration. As indicated here, even most simple liquids will exhibit some elastic response at shear rates or frequencies exceeding 5 x 10 cycles per second. Experiments on such
Oh Dear! What Can the Matter Be? we do think that we are sadly neglected; Because they don't visit the school. </poem> Oh Dear! What Can the Matter Be? "What Can the Matter Be?", also known as "Johnny's So Long at the Fair" is a traditional nursery rhyme that can be traced back as far as the 1770s in England. There are several variations on its lyrics. The "Oxford Dictionary of Nursery Rhymes" by Iona and Peter Opie traces this song back to an earlier folk ballad, recorded between 1770 and 1780, whose lyrics are: <poem> O what can the matter be And what can the matter