Question

I'm stuck on number 4... help please?

Answer 1

$V= \frac{\Delta S}{\Delta t} = \frac{5}{15} = \frac{1}{3} m/s$

Answer 2

Average speed = (distance covered) / (time to cover the distance) =
 
                                     (5m)  /  (15 sec) =

                                     (5/15) (m/s)  =  1/3 m/s .

Average velocity = 

         (displacement) / (time spent traveling)  in the direction of the displacement

Average velocity =  (5m) / (15 sec)  left =

                           (5/15) / (m/sec)  left  =

                               1/3  m/s  left.

A number without a direction is a speed, not a velocity.