The figure shows the v - t graph of a particle moving in a straight line. Starting from rest, the time after which the particle returns to its starting position is ​

Step-by-step solution

For a particle to return to origin. Net displacement is zero. For t = 0 to t = 20 s , a 1 = 20 20 = 1 m s - 2 For t = 20 s to t s , a 2 = 0 - 20 25 - 20 = - 4 m s - 2 0 = 1 2 × 2 0 × 2 5 + 1 2 × - 4 × t - 2 5 2 ( t - 25 ) 2 = 125 t - 25 = ± 11 . 2 t > 25 s t = 36 . 2 s