calculate the distance travelled by a bus when,

u = 60 km / hr = 60 x 5 / 18 = 50 / 3 m/s

v = 0; t = 1 / 15 s

using

v = u + a t

0 = 50 / 3 + a x 1/15

a = - 50 x 15 / 3 = - 250 m/s²

and

v² = u² + 2 a s

0 = (50/3)² + 2 x (- 250) x s

s = 50 x 50 / 3 x 3 x 2 x 250 = 10 / 18 m

similarly you can solve it for 1/ 2 sec