Question

a car traveling at 30km/h brought to rest

Answer 1

COMPLETE QUESTION :-

At a car travelling at a speed of 30 km/h is brought to rest in a distance of 8 m by applying brakes if the same car is moving at a speed of 60 km/h then it can be brought to rest with same brakes in how much time?

SOLUTION :-

S = u² / (2a)

Same car will cause same retardation/deceleration (a) in both cases.

∴ S ∝ u²

S₁ / S₂ = (u₁ / u₂)²

⇒S₂ = S₁ × (u₂ / u₁)²

⇒S₂ = 8 × (60 / 30)²

⇒S₂ = 32 m

It will come to rest after 32 mins.