Question

The stopping distance d of a car after the brakes are applied varies directly as the square of the speed r. If a car travelling 70 mph can stop in 270 ft, how many feet will it take the same car to stop whenit is travelling 60 mph?

Answer 1

270/70^2 = x/80^2

Cross multiply

270 (6400) = 4900x

x = 270(6400)/4900

352 and 32/49 feet

Hope this helps