Study the given velocity-time graph and answer the following questions:
$(i)$ Which part of the graph shows accelerated motion?
$(ii)$ Which part of the graph shows retarded motion?
$(iii)$ Calculate the distance travelled by the body in the first $4 \ s$ of the journey graphically.

(N/A) $(i)$ The part $AB$ of the graph shows acceleration,as the velocity increases with time.
$(ii)$ The part $CD$ of the graph shows retardation (deceleration),as the velocity decreases with time.
$(iii)$ The distance travelled is equal to the area under the $v-t$ graph.
For the first $4 \ s$,the area is represented by the triangle $ABE$.
Distance $S = \text{Area of } \Delta ABE = \frac{1}{2} \times \text{base} \times \text{height}$
$S = \frac{1}{2} \times (AE) \times (BE)$
$S = \frac{1}{2} \times 4 \ s \times 4 \ m/s = 8 \ m$.