Speed: Formula and units
In a nutshell
Speed is a measure of how much distance is travelled within a certain amount of time.
Formula for speed
The formula to calculate speed is:
speed=timedistance
Or, more simply:
S=TD
Units of speed, distance and time
measurement
| units
|
| Speed
| metres per second ( m/s), kilometres per hour ( km/h), miles per hour (mph) |
| Distance
| metres ( m), kilometres ( km), miles ( miles) |
| Time
| seconds ( s), hours ( h) |
Solving speed problems
To solve problems involving speed, follow this procedure:
procedure
| 1.
| Identify what values you have and what variable you want to find.
|
| 2.
| Rearrange the speed formula for the desired variable.
|
| 3.
| Substitute in known values.
|
| 4.
| Give the answer with the correct units.
|
Example
A car has travelled 250 kilometres in 5 hours. What was the speed of the car?
From the given information, identify the distance and the time:
D=250km,T=5 hours
Write the speed formula (no need to rearrange as it's already given in terms of speed):
S=TD
Substitute in the known values:
S=5h250km
Give the answer with the correct units:
S=50km/h
