Question

A car traveling at speed v takes distance d to stop after the brakes are applied. What is the stopping distance if the car is initially traveling at speed 2v? Assume the acceleration for braking is the same in both cases.

Answer 1

4d

Step-by-step explanation:

At initial speed v:

v² = u² + 2as

(0)² = (v)² + 2a(d)

a = -v²/(2d)

At initial speed 2v:

v² = u² + 2as

(0)² = (2v)² + 2(-v²/(2d)) s

0 = 4v² − (v²/d) s

s = 4d

Doubling the initial speed results in quadruple the stopping distance.