(Any unit of distance)
divided by
(any unit of time)
becomes a unit of speed. Some favorites are mile/hour,
meter/second, and foot/second.
Speed is a part of velocity, so the same units are involved
in velocity. But velocity needs more than that.
When you have the distance and the time, you know the
speed completely ... there's no more to know about it.
But speed is only part of velocity. In addition to speed,
there's more to know in order to have a velocity. That's
the direction of the speed.
