Vibration of vibration are pulling a child back on a swing and letting it go, or hitting a tuning fork and letting it ring. The mechanical system vibrates at one or more of its natural frequencies and damps down to motionlessness. Forced vibration is when a time-varying disturbance (load, displacement or velocity) is applied to a mechanical system. The disturbance can be a periodic and steady-state input, a transient input, or a random input. The periodic input can be a harmonic or a non-harmonic disturbance. Examples of these types of vibration include a washing machine shaking due to an imbalance, transportation
Oh Dear! What Can the Matter Be? basin it was the same water the next washed her face in – and nobody knew they were there. </poem> "Seven Old Ladies" was not the first parody, however. Long before that parody, the song had been parodied for political purposes. One such parody can be found in the "Wisconsin State Journal" of 1 March 1864. It was written to exhort parents, who during the U.S. Civil War had not taken much interest in public schooling in Madison, to visit the schools of their children. Its lyrics were: <poem> Oh, dear, what can the matter be? Oh, dear, what can