Alex is zooming around a flat, circular highway exit ramp in his sportscar, moving at a constant speed of v = 10.0 m/s. He notices that his necklace, which hangs from the rearview mirror at the end of a massless cord of length L = 5.0 cm is hanging so that it is W = 4.0 cm from the point directly below the mirror. Find the radius of the circular exit ramp. Your answer should be a number.