Question

An object travels North at `8 ms^-1` for `7 s` and then travels South at `7 ms^-1` for `3 s`. What are the object's average speed and velocity?

Answer 1

Average speed:

`speed=("distance")/(time)=56/10=5.6` `ms^-1`

Average velocity:

`velocity=("displacement")/(time)=21/10=2.1` `ms^-1`

Explanation:

In brief, the average speed relates to the distance traveled, the average velocity to the displacement.

Distance traveled North: `d=vt=8*7=56` `m`
Distance traveled South: `d=vt=7*3=21` `m`

Total distance traveled: `77` `m`
Displacement: `35` `m`

Total time taken: `10` `s`

Average speed:

`speed=("distance")/(time)=56/10=5.6` `ms^-1`

Average velocity:

`velocity=("displacement")/(time)=21/10=2.1` `ms^-1`