Explanation

(c) From equation of motion, we have
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ s = ut + \frac{1}{2}\ at^{2}$
When $s = 24\ m,\ t = 4\ s,$
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 24 = 4u + \frac{1}{2}\ a(4)^{2}$
Or $\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 24 = 4u + 8a$
Or $\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 6 = u + 2a\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ldots.(i)$
When body travels a total distance of $24 + 64 = 88\ m\ in\ 8\ s,\ $we get
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 88 = 8u + \frac{1}{2}a\ (8)^{2}$
Or $\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 88 = 8u + 32a$
Or $\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 11 = u + 4a\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ldots.(ii)$
Solving Eqs. (i) and (ii), we get
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ u = 1\ {ms}^{- 1}$