(1/2)mv^2 = mgh
(1/2)v^2 = gh

h = (1/2)v^2 / g ≒ (1/2g) v^2

v = V km/h = V*1000/3600 = V*5/18
h = (1/2g * (5/18)^2 ) V^2
= 0.004 V^2

V = 60 km/h

h = 0.004*60^2 = 14.4m