Question

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?

Answer 1

`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`