A car starting from rest accelerates at the rate f through a distance S, then continues at constant speed for time t and then decelerates at the rate f/2 to come to rest. If the total distance traversed is 15 S, then
(1) S=ft
(2) S = 1/6 ft2
(3) S = 1/2 ft2
(4) S = 1/4 ft2
