A person is standing on a second-floor balcony drops keys to a friend standing below the balcony. The keys are dropped from a height of 10 feet. The height in feet of the keys as they fall is given by the function h(t) = 16t2 + 10, where t is the time in seconds since the keys were dropped. The friend catches the keys at a hight of 4 feet. Find the elapsed time before the keys are caught.