A sphere is attached by a string to the roof of an automobile tunnel in order to provide the tunnel operators with a simple estimate of the wind speed V blowing through the tunnel. Here is some more information: The diameter of the sphere is D = 2.23 cm The specific gravity of the sphere is SG = 0.865 Buoyancy forces may be neglected, assuming that the specific gravity was measured in air such that buoyancy has already been taken into account The air temperature and pressure are 25o C and 101.325 kPa, respectively, which are SATP conditions