9. If a particle has an initial velocity of v. 12 ft/s to the right, at s, 0, determine its position when t = 8s, if a 2 ft/s² to the left. = (a) s = 160 ft (b) s=32 ft (c) s = 170 ft (d) s = 20 ft 10. A particle travels along a straight line with a velocity v = (12-3t2) m/s, where t is in seconds. When t = 1 s, the particle is located 10 m to the left of the origin. Determine the acceleration when t = 4 s. (a) a = 24 m/s² (b) a = -42 m/s² (c) a = -24 m/s² (d) a = 20 m/s² 11. A particle travels along a straight line with a constant acceleration. When s = 4ft, v = 5 ft/s, and when s 10 ft, v = 10 ft/s. Determine the acceleration of the particle. (a) a = 5.34 ft/s² (b) a = 6.25 ft/s² (c) a = 4.58 ft/s² (d) a = 6.23 ft/s²