In the figure,a time-distance graph of a linear motion is given. Two positions of time and distance are recorded as: when $T = 0, D = 2$ and when $T = 3, D = 8$. Using the concept of slope,find the law of motion,i.e.,how distance depends upon time.

(N/A) Let $(T, D)$ be any point on the line,where $D$ denotes the distance at time $T$.
Since the points $(0, 2)$,$(3, 8)$,and $(T, D)$ are collinear,the slope between any two pairs of points must be equal.
Slope $= \frac{8 - 2}{3 - 0} = \frac{D - 8}{T - 3}$
$\frac{6}{3} = \frac{D - 8}{T - 3}$
$2 = \frac{D - 8}{T - 3}$
$2(T - 3) = D - 8$
$2T - 6 = D - 8$
$D = 2T + 2$
$D = 2(T + 1)$
This is the required relation.