Question 275400
I flew from Pheonix to Tucson, a distance of 120 miles, at a constant speed of 120 mph, I then returned at a constant speed of 60 mph. 
what is my average speed? 240/3 = 80 mph
trip distance?  240 miles
displacement? relative to what?
and average velocity? Velocity is a vector that includes speed and direction.  It's often used to mean speed, and speed has already been calculated.
I don't think averages apply to vectors, either.
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