A particle moves along a straight line. Answer the following with reference to its velocity–time description:
(i) Define displacement and distance travelled.
(ii) Explain, with suitable reasoning, why the algebraic area enclosed between a velocity–time curve and the time-axis between two instants gives the displacement of the particle for that interval.
(iii) If the velocity becomes negative for a certain part of the motion, describe the procedure you would follow to obtain (a) the net displacement and (b) the total distance travelled from the same velocity–time graph without performing any algebraic calculation.