Ahorse trots away from its trainer in a straight line, moving 38 m away in 9.0 s. it then turns abruptly and gallops halfway back in 1.8 s. calculate (a) its average speed and (b) its average velocity for the entire trip, using âaway from the trainerâ as the positive direction.

a. Average speed = distance / total time

distance = 38 meters (going away) + 38 meters (going back) = 76 meters

total time = 9 seconds (going away) + 1.8 seconds (going back) = 10.8 seconds

Average speed = 76 meters / 10.8 seconds = 7.04 m/s

b. Average velocity = displacement / total time 
Displacement = Final position – Initial position 

Initial position = 0 m 
Final position = 0 m (since it gallops back to the trainer)
Displacement = 0 m – 0 m = 0 
total time = 10.8 seconds 

Average velocity = 0 / 10.8 = 0 m/s