# An object travels North at #7 m/s# for #4 s# and then travels South at #6 m/s# for # 7 s#. What are the object's average speed and velocity?

##### 3 Answers

The average speed is

#### Explanation:

The total distance travelled is

The total time is

The average speed is

The apparent distance travelled is

The average velocity is

Interpreting the question to be asking for 'displacement'

#### Explanation:

Let the Northern vector be positive.

So the Southern vector is negative.

Let the resultant be

Thus we have:

The displacement (resultant)

So a better representation is:

The total time for this displacement to be occurring is

Note that in how I set this up a **negative value means south** from the starting point.

So the average

In decimal form this is

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Average speed:

Average speed

Average speed

Average velocity

#### Explanation:

- Let unit vector along North be
#hatj# . So, unit vector along South will be#-hatj#