Question

A police officer observes a motorist who is approaching at a uniform speed of

80kmph. He, in his patrol car, starts chasing it as it just crosses him. After

accelerating for 8seconds at a constant rate, he attains his top speed of 120kmph. How

long does it take to overtake the motorist and at what distance?​

Answer 1

Answer:

Initial velocity of the motorist (u) = 120+80 = 200kmph = 55m/s

Final velocity (v) = 0

Acceleration (a) = 8m/s^2

Applying v^2-u^2=2as

0^2 - 55^2 = 2×8×s

3025 = 16s

S = 3025/16

= 189m

Applying S=ut+1/2at^2

189 = 55×t+1/2×8×t^2

189 = 59t

t = 3min 2sec