An automobile travelling with a speed of 60 km/h, can brake to stop within a distance of 20 m. If the car is going twice as fast, i.e. 120 km/h, the stopping distance will be
(a) 20 m
(b) 40 m
(c) 60 m
(d) 80 m.
(d) : Let a be the retardation for both the vehicles For automobile, v 2 = u 2 – 2 as
Similarly for car, u22 = 2as 2
