Åk 6–9

English/فارسی
3.3 Average Velocity
Image that you are riding your moped to a friend’s.  During the journey, you probably don’t keep the same velocity.  You accelerate, break and stop.  Sometimes your velocity is 10 km/h and sometimes its 30 km/h.

Average velocity is the total distance you have traveled during the journey during the total time.

You can show average velocity by using a diagram.

Here below you see the distance-time diagram for how Veronica rides a moped from home to a friend’s.

Here the dotted lines is the moped’s average velocity.

 From the diagram, we can determine that it is 50 km to her friend’s and it too Veronica 1.25 h. (1 hour and 15 minutes) to get there. Average Velocity = d ÷ t = 50 km ÷ 1.25 h = 40 km/h

Here are a few calculation examples of average velocity:

Example A

It took William 3 hours to walk 18 km. What average velocity did he have? Answer in km/h.

Velocity v = d ÷ t
distance d = 18 km
Time t = 3 h

Velocity = d ÷ t = 18 km ÷ 3 h = 6 km/h

Answer: William’s average velocity was 6 km/h

Example B
 Max went out bicycling. In the diagram to the right, you can see a description of his trip.

Example C

Justin travelled with an average velocity of 30 m/s for 3 hours.  How many Swedish Miles (1 mile = 10 km) did Justin travel?

d = v · t
v = 30 m/s = (3.6 · 30) km/h = 108 km/h
t = 3 h
d = 108 km/h · 3 h = 324 km = 32.4 mil

Answer: Justin travelled 32.4 mil.