Once upon a time, a stunt man named Evil Knievel boasted that he would jump across the Grand Canyon on a motorcycle. (This stunt was never attempted.) The width of the Grand Canyon varies from place to place, but suppose that Mr. Knievel attempts to jump across at a point where the width is about 4.18 miles, and the two rims are at the same altitude. What minimum initial speed would be required to make it safely across the canyon? Express your answer in m/s and mph. Ignore air drag.