Originally commissioned by the Opera del Duomo for the Cathedral of Florence, it was meant to be one of a series of large statues to be positioned in the niches of the cathedral's tribunes, way up at about 80mt from the ground. David was originally commissioned as one of a series of statues of prophets to be positioned along the roofline of the east end of Florence Cathedral, but was instead placed in a public square, outside the Palazzo Vecchio, the seat of civic government in Florence, in the Piazza della Signoria, where it was unveiled on. Hope this helps!
Yes it's true, but that doesn't last very long. It creates a compression of the molecules during exactly half of each vibe, and during the other half, it leans the other way, and the molecules spread out in what's called a "rarefaction" a region of lower-than-normal pressure. This 'train' of compressions and rarefactions is what travels through the air, away from the vibrating object, and it's what some people often call a "sound wave".
