An object travels North at # 7 m/s# for #6 s# and then travels South at # 3 m/s# for # 3 s#. What are the object's average speed and velocity?

1 Answer
Oct 8, 2016

Answer:

#color(green)("Average speed: "5 2/3 " m/s")#

#color(blue)("Average velocity: "3 2/3 " m/s North")#

Explanation:

Distance:
#color(white)("X")#First #6s#: #color(white)("XX")7m/s * 6 s = 42 m#
#color(white)("X")#Last #3x#: #color(white)("XX")3m/s * 3 s = 9 m#
Total distance traveled: #42m + 9 m = 51 m#
over a period of #6s + 3s = 9s#
for an average speed of #51/9 m/s = 5 2/3 m/s#

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Displacement:
#color(white)("X")#First #6s#: #color(white)("XX")7 m/s N * 6 s = 42 m N#
#color(white)("X")#Last #3s#: #color(white)("XX")3 m/s S* 3 s =9 m S = -9 m N#
Total displacement traveled: #42 m N + (-9) m N = 33 m N#
over a period of #6s + 3 s = 9s#
for an average velocity of #33/9 m/s N = 3 2/3 m/s N#