Metric Speed (Velocity)
These are the most common measurements:
- Meters per second (m/s)
- Kilometers per hour (km/h)
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.
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 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
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