Question

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

Answer 1

`Avg. Speed = 57/7 ms^-1`
`Avg. Velocity = 15/13 ms^-1` (northwards)

Explanation:

`Avg Speed = (Total Dist.) / (Total time)`
`= (6xx6 + 3 xx 7)/(6 + 7) = 57/13 m/s`
(Distance = Speed x Time)
Total Displacement is 36 - 21. The object went 36 m north and then 21 m south. Thus it is displaced by 15 m from its origin. `Avg. Velocity = (Total Displacement)/(Total time)`
`= 15/(6+7) = 15/13 m/s`

You may wish to specify that the displacement is in the north direction.