In this subsection is about the concept of speed. The speed
of an object indicates how far it travels in a particular period of time.
Therefore
In 1 hour you cover (40×1) = 40km
In 2 hours you cover (40×2) = 80km
In 3 hours you cover (40×3) = 120km
In 4 hours you cover (40 ×4) =160km
Metres per second of miles per hour. There are all examples
of compound units. Because they
involve more than one basic unit of measurement.
Instead the average speed for a journey is used in
calculations.
The average speed for a journey is calculated using the
formula below.
Average speed = 
This formula is often written more
concisely as
Average speed = 
or speed = 
or speed =
The unit to measure the speed from the
unit for the distance and the time.
Example 3 finding an average
speed
Suppose that a car travels
a distance of 75km in 45 mins on a motorway. What is the average speed? Give you
answer in km/h
Solution
First method
Use the formula to find the
average speed in km/min and then covert to km/h
The distance is 75km and
the time is 45 min. so by the formula
Average speed = 
km/min =1.666 km/min
km/min =1.666 km/min
Now convert this answer to
km/h by multiplying the full calculator value for the distance travelled in 1
min by the number of minutes in an hour.
There are 60 mins in an
hour, so
Average speed = (1.666×60)
km/h = 100km/h
Second method
Convert the time to hours
and then find the average speed in km/h
First 45 mins is 
of an hour that is 0.75h. So by the formula
of an hour that is 0.75h. So by the formula
Average speed = 
km/h = 100km/h.
km/h = 100km/h.
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