Question

An object travels North at `8 m/s` for `3 s` and then travels South at `6 m/s` for `7 s`. What are the object's average speed and velocity?

Answer 1

average speed: 6.6 m/s
average velocity: 1.8 m/s South

Explanation:

Object travels North at `8m/s` for `3s`
`rarr` object travels `8m/sxx3s=24 m " North"`
then
it travels South at `6 m/s` for `7 s`
`rarr` object travels `6m/sxx7 s=42 m " South"`

Total distance traveled: `24 m +42 m =66 m`

Total displacement from point of origin:
`color(white)("XXX")24 m N +42 m S=-24m S +42 m S=18 m S`

Total time involved in travel: `3 s+7s=10s`

`"Average speed" = ("total distance")/("total time") =(66 m)/(10 s)=6.6m/s`

`"Average velocity"=("total displacement")/("total time")=(18 m S)/(10 s) =1.8 m/s S`