Velocity!

Average velocity

v = d / t

That is, displacement divided by time.

Some velocities to ponder....
Approximately....

Keep in mind that 1 m/s is approximately 2 miles/hour.

Your walking speed to class - 1-2 m/s
Running speed - 5-7 m/s
Car speed (highway) - 30 m/s
Professional baseball throwing speed - 45 m/s
Terminal velocity of skydiver - 55 m/s
Speed skiing - 60 m/s
Speed of sound (in air) - 340 m/s
Bullet speed (typical) - 900 m/s
Satellite speed (in orbit) - 6200 m/s
Escape velocity of Earth - 11,200 m/s
(That's around 7 miles per second, or 11.2 km/s)

Speed of light (in a vacuum) -
c = 299,792,458 m/s

This number is a physical constant, believed to be true everywhere in the universe. The letter c is used to represent the value being of constant celerity (speed).

This speed is SO fast that:

it's around 7 times around the Earth's equator in one second
it's up to the Moon and back in around 2.5 seconds
it's out to the Sun in around 8 minutes
it's around 186,000 miles per second

LIGHT UNITS (for distance):

Related to this, we call the distance that light can travel (unimpeded) in one year a "light year". Other useful distinctions:

light-second -- around 300,000,000 m (or 186,000 miles)
light-minute -- 60 times the above number
light-year -- 60 x 60 x 24 x 365.35 times the above number

A light year is a big distance to us, but astronomically speaking, it's tiny. The nearest star (our Sun) is around 8 light MINUTES, but the nearest star other than the Sun is around 4.2 light YEARS away! It's Proxima Centauri, by the way, but it's not visible to the naked eye. Alpha Centauri (a binary system system) IS visible (Southern Hemisphere), and it's around 4.3 light years away.

FYI:

http://en.wikipedia.org/wiki/List_of_nearest_stars

http://en.wikipedia.org/wiki/Alpha_Centauri