Question

The stopping distance (s) of a car varies directly as the square of its speed (v). If a car traveling at 50 mph requires 170 ft to stop, find the stopping distance for a car traveling at
v2 = 55
mph.

Answer 1

we have s = kv^2
That is, s/v^2 is constant. So, now we know that

170/50^2 = x/55^2

Note that we don't really need to know the value of k, just that it is constant.