Please answer this question.

Dear Student,

Let t = Time interval to meet student and bus Condition to meet : Distance travelled by student = Distance travelled by bus + 50 m ut = \frac{1}{2} {at}^{2} + 50 u = \frac{1}{2} at + \frac{50}{t} for minimum value of u, \frac{du}{dt} = 0 \frac{du}{dt} = \frac{1}{2} a - \frac{50}{t^{2}} 0 = \frac{1}{2} a - \frac{50}{t^{2}} \frac{50}{t^{2}} = \frac{a}{2} t^{2} = \frac{100}{a} = \frac{100}{1} t = 10 s Hence, u = \frac{1}{2} at + \frac{50}{t} = [\frac{1}{2} \times 1 \times 10] + \frac{50}{10} = 10 m / s Ans : 10 m / s

Therefore, option 3 is correct.
Regards