Answer
(a) According to the slope, average velocity is positive for segments A and C, negative for segment B, and zero for segment D.
(b)$V_{A}=6.3\space km/h$ ,$V_{B}=-3.8\space km/h$ , $V_{C}=0.63\space km/h$ ,$V_{D}=0\space km/h$
Work Step by Step
The average velocity is given by the slope of a straight-line segment in a position-versus-time graph. The algebraic sign of the average velocity, therefore, corresponds to the sign of the slope.
(b)$V_{A}=\frac{1.25\space km-0\space km}{0.2\space h-0\space h}=6.3\space km/h$
$V_{B}=\frac{0.5\space km-1.25\space km}{0.8\space h-0.4\space h}=-3.8\space km/h$
$V_{C}=\frac{0.75\space km-0.5\space km}{0.8\space h-0.4\space h}=0.63\space km/h$
$V_{D}=\frac{0.75\space km-0.75\space km}{1\space h-0.8\space h}=0\space km/h$
