This is a basic physics tutorial that is targeted at GCSE (grade 9 and grade 10) standard.
The last two tutorials covered what speed is, and what distance-time graphs are, including how to calculate the average speed from one. This tutorial delves into distance-time graphs a little further by exploring return journeys.
What is a return journey?
A return journey is exactly what it sounds like: it's a journey that includes setting out to go somewhere, and then returning back at your original place. An example is illustrated in the graph below.
The orange line represents the initial journey, whereby an object has traveled 10km in an hour. The green line represents the person staying at their destination for an hour and a half. The purple line represents the journey the object has taken to return to its original place; it represents the object traveling 10km 'home' over four hours.
Calculating the average speed of each portion of the journey is as simple as calculating the slope of the line that represents the journey (as below).
Want some more examples?
An example is covered in the above video. Below is an exercise worksheet that includes other journeys with multiple legs (multiple stops) to them (NB: one is a return-journey, the other is simply a journey with multiple stops).