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
Alan P.
Oct 8, 2016

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

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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

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