Question

A car moving with a speed of 40 km/h can be

stopped by applying brakes after at least 2 m. If

the same car is moving with a speed of 80 km/h,

what is the minimum stopping distance?

(a) 2 m (b) 4 m (c) 6 m (d) 8 m
​

Answer 1

S = u² / (2a)

For same car “a” is constant.

So,

S ∝ u²

S₂ / S₁ = (u₂ / u₁)²

S₂ = S₁ × (u₂ / u₁)²

= 2 m × (80 / 40)²

= 2 m × 4

= 8 m

Stopping distance of car will be 8 m