The following displacement-time graph shows the positions of a body at different times. Calculate the velocity of the body as it moves from: $(i) A-B, (ii) B-C, (iii) C-D$.

(N/A) Velocity is determined by the slope of the displacement-time graph,where $V = \frac{\Delta \text{displacement}}{\Delta \text{time}}$.
$(i)$ For segment $A-B$: The displacement changes from $0 \ m$ to $3 \ m$ in the time interval from $2 \ s$ to $5 \ s$.
$V_{AB} = \frac{3 - 0}{5 - 2} = \frac{3}{3} = 1 \ m \ s^{-1}$.
$(ii)$ For segment $B-C$: The displacement remains constant at $3 \ m$ from $5 \ s$ to $7 \ s$.
$V_{BC} = \frac{3 - 3}{7 - 5} = \frac{0}{2} = 0 \ m \ s^{-1}$.
$(iii)$ For segment $C-D$: The displacement changes from $3 \ m$ to $0 \ m$ in the time interval from $7 \ s$ to $10 \ s$.
$V_{CD} = \frac{0 - 3}{10 - 7} = \frac{-3}{3} = -1 \ m \ s^{-1}$.