How would you explain speed to a Martian (alien)

‘Speed’ has various different definitions. If the occasion arose that I were to explain that word to him I would    list it’s meanings, their contexts and an example of each.

The first of it’s meanings is the swiftness of an action. It generally means the act of moving quickly. It is used in many contexts which involve a movable object. An example of such is in a bike race: The man peddled along with great speed

It can also used in terms the terms of physics. Such as that of the rate of motion. It is the overall distance travelled divided by the time taken. An example of were it might be used is by taxi owner. It is maybe necessary for one to work out how long a trip will take using the above formula.

The following terms are seldom use except for when speaking in a technical terms

          1 A numerical expression of the sensitivity of a       photographic film, plate, or paper to light.

          2. The capacity of a lens to accumulate light at an   appropriate aperture.

          3. The length of time required or permitted for a camera   shutter to open and admit light

Speed is pronounced sp d . The pronunciation of the styled ‘e’ can be found in most dictionaries. It can be used as either a verb or a known as appropriate. It is also used in the well known idiom: Up to Speed. This means operating at full capacity