An object travels North at #6 m/s# for #5 s# and then travels South at #7 m/s# for # 5 s#. What are the object's average speed and velocity?

1 Answer
Jan 14, 2018

Answer:

Average speed #=6.5m/s#
Average velocity# = -0.5m/s#

Explanation:

Average # "velocity" = "displacement"/"time elapsed"#
#bar v = (Deltax)/(Delta t) #
Average # "speed" = "distance traveled"/"time elapsed"#
#bar s = d/(Delta t) #

Going north at 6m/s for 5s is 30m, and going south at 7m/s for 5s is 35m, hence the object in 10s has effectively gone south for 5m as a displacement despite it has actually traveled a total distance of 65m.

Bear in mind that for displacement going north is positive, south negative:

#Delta x = 6m/s*5s - 7m/s*5s= 30m-35m= - 5m#

#d = 30m + 35m = 65 m#

#Delta t = 5s+5s = 10s#

#bar v = (Deltax)/(Delta t) =-(5m)/(10s) = -0.5m/s #
#bar s=d/(Delta t)=(65m)/(10s) = 6.5 m/s#