Question

An object travels North at `5 m/s` for `6 s` and then travels South at `8 m/s` for `4 s`. What are the object's average speed and velocity?

Answer 1

Refer to the explanation.

Explanation:

The total distance traveled was:

`5 \ "m/s"*6 \ "s"+8 \ "m/s"*4 \ "s"`

`=30 \ "m"+32 \ "m"`

`=62 \ "m"`

So, the average speed is:

`bars=d/t`

`=(62 \ "m")/(10 \ "s")`

`=6.2 \ "m/s"`

I'll take North to be the original direction for velocity. So, the total displacement is:

`5 \ "m/s"*6 \ "s"-8 \ "m/s"*4 \ "s"`

`=30 \ "m"-32 \ "m"`

`=-2 \ "m"`

So, the displacement is `2 \ "m"` south.

The average velocity is therefore:

`barv=(vecd)/t`

`=(-2 \ "m")/(10 \ "s")`

`=-0.2 \ "m/s"`

This means that the average velocity is `0.2 \ "m/s"` south.