Final answer:
In public parking garages, vehicle barriers must be a minimum of 36.6 m (120 ft) in height.
Step-by-step explanation:
In public parking garages, vehicle barriers must be a minimum of 36.6 m (120 ft) in height. This is because the potential energy of a vehicle parked on the top level of a parking garage is equivalent to the amount of work required to raise the vehicle from street level to the top level. According to the equation PE=mad= mgh, where m is the mass of the vehicle and h is the height of the parking garage, the minimum height must be at least 36.6 m (120 ft) in order to raise the vehicle to the top level.