An Alfa Romeo going at 70 mph requires 164 feet to stop.

Question

An Alfa Romeo going at 70 mph requires 164 feet to stop. Assuming that the stopping distance is proportional to the square of velocity, find the stopping distances required by an Alfa Romeo going at 35 mph and at 140 mph (its top speed).

At 35 mph: ?

At 140 mph: ?

Answer 1

D = k * V^2

164 = k * 70^2

164 = k* 4900

k = 164/4900 = 82/2450 = 41/1225

D = (41/1225)* V^2

V= 35 ---> D=41

V=140 ---> D=656