Reading the source code----- I took the source code from one that was used to calculate the MSD, and I didn't change the names of variables. So to make sense of these variables: PosX = VelX of ...

A school bus is travelling at 4 m/s. Its velocity then increases to 12 m/s. Calculate the average velocity of the bus over the journey. Final velocity = 12 m/s. Initial velocity = 4 m/s.