Question

solve question no 34 of physics

Answer 1

Option D ..might be the right one as this satisfies the equation
3t^2+25t+50
3t^2+15t+10t+50
3t(t+5) +10(t+5)
T= -5 or 3t=10
As time cannot be negative so t=10/3
3.33 sec

Answer 2

A is the position of policeman in the beginning.
B is the position of theif before its start running.
C is the position when the policeman catches the theif.

AB = 50m

Let us assume that the policeman catches the theif in t seconds. So, the theif travels 25t distance in t seconds while travelling with 25m/s. So, this means that the policeman has to travel 50+25t metres to catch the theif.

The policeman starts from rest and accelerates at 6m/s² and covers a distance of 50+25t m to catch the theif.

Now we just use the 2nd equation of motion in policeman's journey and calculate the time.

s = ut + at²/2
50+25t = 0×t + 6×t²/2
3t²-25t-50=0
(3t+5)(t-10)=0
t = 10 sec or -5/3 sec

Since time can't be negative, t= 10 sec.

Hence, option​ (1) is correct.

I hope you understand the approach.
All the best!