Metric Speed (Velocity)

These are the most common measurements:

  • Meters per second (m/s)
  • Kilometers per hour (km/h)

walking

 

Speed in meters per second (m/s)

If something is traveling at 1 m/s it moves 1 meter every second.

It is a gentle walking speed.

One hour walking at 1 m/s moves you 3.6 km.


Speed in kilometers per hour (km/h)

If something is traveling at 1 km/h it moves 1 kilometer every hour.

It is like a very slow walking speed.

Kilometers per hour is often used for car speeds.

Example: Highway speed is around 100 km/h

One hour at this speed moves you 100 km.

Example: One minute at 60 km/h moves you 1 km.

Converting

You can convert from m/s to km/h:

  • 1 m/s = 3.6 km/h
  • 1 km/h = 0.2777... m/s

Example: What is 100 km/h in m/s?

A kilometer has 1,000 meters, and an hour has 3,600 seconds, so 100 kilometers per hour is:

  • 100 x 1,000 / 3,600 = 27.777... m/s

100 km/h = 27.78 m/s (to 2 decimal places)

Velocity

Velocity is speed with a direction.

So if something is moving at 5 km/h that is a speed.

But when we say it is moving at 5 km/h westwards that is a velocity.

If something moves backwards and forwards very fast it has a high speed, but a low (or zero) velocity

Examples

100 km/h is about:

  • how fast we can legally go on many highways
  • the maximum running speed of a cheetah
  • half the freefall speed of a skydiver

60 km/h is about:

  • going very fast on a bicycle
  • the speed needed to go one kilometer in a minute
  • the speed of a racehorse on a short track
  • full running speed of a Bengal Tiger

1 meter per second is:

  • about 3.2808 feet per second

1 kilometer per hour is

  • about 0.9113 feet per second