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