(a) Sand dunes on a desert island move as sand is swept up the windward side to settle in the leeward side. Such "walking" dunes have been known to travel 24 feet in a year and can travel as much as 105 feet per year in particularly windy times. Calculate the average speed in each case in m/s.
(b) Fingernails grow at the rate of drifting continents, about 10mm/yr. Approximately how long did it take for North America to separate from Europe, a distance of about 3540 miles?
Note I would also like to see the problems solved as opposed to only the answers. Thanks a bunch.